diff --git a/sm4/xts_arm64.s b/sm4/xts_arm64.s
index e92dbc3..277d01b 100644
--- a/sm4/xts_arm64.s
+++ b/sm4/xts_arm64.s
@@ -526,6 +526,197 @@ xtsSm4EncDone:
 
 // func decryptSm4Xts(xk *uint32, tweak *[BlockSize]byte, dst, src []byte)
 TEXT ·decryptSm4Xts(SB),0,$128-64
+	LOAD_SM4_AESNI_CONSTS()
+	MOVD xk+0(FP), rk
+	MOVD tweak+8(FP), twPtr
+	MOVD dst+16(FP), dstPtr
+	MOVD src+40(FP), srcPtr
+	MOVD src_len+48(FP), srcPtrLen
+
+	VEOR	POLY.B16, POLY.B16, POLY.B16
+	VEOR	ZERO.B16, ZERO.B16, ZERO.B16
+
+	MOVD	$0x87, I
+	VMOV	I, POLY.D[0]
+
+	MOVD rk, rkSave
+	VLD1 (twPtr), [TW.B16]
+
+xtsSm4DecOctets:
+	CMP	$128, srcPtrLen
+	BLT	xtsSm4DecNibbles
+	SUB	$128, srcPtrLen
+
+	prepare8Tweaks
+	load8blocks
+	MOVD rkSave, rk
+	EOR R13, R13
+
+decOctetsDec8Blocks:
+			SM4_8BLOCKS_ROUND(rk, R19, K0, K1, K2, K3, B0, B1, B2, B3, B4, B5, B6, B7)
+			SM4_8BLOCKS_ROUND(rk, R19, K0, K1, K2, K3, B1, B2, B3, B0, B5, B6, B7, B4)
+			SM4_8BLOCKS_ROUND(rk, R19, K0, K1, K2, K3, B2, B3, B0, B1, B6, B7, B4, B5)
+			SM4_8BLOCKS_ROUND(rk, R19, K0, K1, K2, K3, B3, B0, B1, B2, B7, B4, B5, B6)
+
+		ADD $1, R13
+		CMP $8, R13
+		BNE decOctetsDec8Blocks
+
+	store8blocks
+	B	xtsSm4DecOctets
+
+xtsSm4DecNibbles:
+	CMP	$64, srcPtrLen
+	BLT	xtsSm4DecSingles
+	SUB	$64, srcPtrLen
+
+	prepare4Tweaks
+	load4blocks
+	MOVD rkSave, rk
+	EOR R13, R13
+
+decNibblesDec4Blocks:
+		SM4_ROUND(rk, R19, K0, K1, K2, B0, B1, B2, B3)
+		SM4_ROUND(rk, R19, K0, K1, K2, B1, B2, B3, B0)
+		SM4_ROUND(rk, R19, K0, K1, K2, B2, B3, B0, B1)
+		SM4_ROUND(rk, R19, K0, K1, K2, B3, B0, B1, B2)
+
+		ADD $1, R13
+		CMP $8, R13
+		BNE decNibblesDec4Blocks
+	
+	store4blocks
+
+xtsSm4DecSingles:
+	CMP	$32, srcPtrLen
+	BLT	xtsSm4DecSingles
+	SUB	$16, srcPtrLen
+
+	loadOneBlock
+
+	MOVD rkSave, rk
+	EOR R13, R13
+
+decSinglesDec4Blocks:	
+		SM4_ROUND(rk, R19, K0, K1, K2, B0, B1, B2, B3)
+		SM4_ROUND(rk, R19, K0, K1, K2, B1, B2, B3, B0)
+		SM4_ROUND(rk, R19, K0, K1, K2, B2, B3, B0, B1)
+		SM4_ROUND(rk, R19, K0, K1, K2, B3, B0, B1, B2)
+		ADD $1, R13
+		CMP $8, R13
+		BNE decSinglesDec4Blocks
+
+	storeOneBlock
+	mul2Inline
+
+	B	xtsSm4DecSingles
+
+xtsSm4DecTail:
+	CBZ	srcPtrLen, xtsSm4DecDone
+	
+	CMP	$16, srcPtrLen
+	BEQ xtsSm4DecLastBlock
+
+	VMOV TW.B16, B4.B16
+	mul2Inline
+	loadOneBlock
+	MOVD rkSave, rk
+	EOR R13, R13
+
+decLastCompleteBlockLoop:	
+		SM4_ROUND(rk, R19, K0, K1, K2, B0, B1, B2, B3)
+		SM4_ROUND(rk, R19, K0, K1, K2, B1, B2, B3, B0)
+		SM4_ROUND(rk, R19, K0, K1, K2, B2, B3, B0, B1)
+		SM4_ROUND(rk, R19, K0, K1, K2, B3, B0, B1, B2)
+		ADD $1, R13
+		CMP $8, R13
+		BNE decLastCompleteBlockLoop
+	storeOneBlock
+	VMOV B4.B16, TW.B16
+	VST1 [B3.B16], (RSP)
+
+	SUB	$16, srcPtrLen
+	SUB $16, dstPtr, R7
+	MOVD R7, R9
+	MOVD RSP, R8
+
+	TBZ	$3, srcPtrLen, less_than8
+	MOVD.P 8(srcPtr), R11
+	MOVD.P R11, 8(R8)
+	MOVD.P 8(R7), R12
+	MOVD.P R12, 8(dstPtr)
+
+less_than8:
+	TBZ	$2, srcPtrLen, less_than4
+	MOVWU.P 4(srcPtr), R11
+	MOVWU.P R11, 4(R8)
+	MOVWU.P 4(R7), R12
+	MOVWU.P R12, 4(dstPtr)
+
+less_than4:
+	TBZ	$1, srcPtrLen, less_than2
+	MOVHU.P 2(srcPtr), R11
+	MOVHU.P R11, 2(R8)
+	MOVHU.P 2(R7), R12
+	MOVHU.P R12, 2(dstPtr)
+
+less_than2:
+	TBZ	$0, srcPtrLen, xtsSm4DecTailDec
+	MOVBU (srcPtr), R11
+	MOVBU R11, (R8)
+	MOVBU (R7), R12
+	MOVBU R12, (dstPtr)
+
+xtsSm4DecTailDec:
+	VLD1 (RSP), [B0.B16]
+	VEOR TW.B16, B0.B16, B0.B16
+	VREV32 B0.B16, B0.B16
+	VMOV B0.S[1], B1.S[0]
+	VMOV B0.S[2], B2.S[0]
+	VMOV B0.S[3], B3.S[0]
+
+	MOVD rkSave, rk
+	EOR R13, R13
+
+tailDecLoop:
+		SM4_ROUND(rk, R19, K0, K1, K2, B0, B1, B2, B3)
+		SM4_ROUND(rk, R19, K0, K1, K2, B1, B2, B3, B0)
+		SM4_ROUND(rk, R19, K0, K1, K2, B2, B3, B0, B1)
+		SM4_ROUND(rk, R19, K0, K1, K2, B3, B0, B1, B2)
+		ADD $1, R13
+		CMP $8, R13
+		BNE tailDecLoop
+
+	VMOV B2.S[0], B3.S[1]
+	VMOV B1.S[0], B3.S[2]
+	VMOV B0.S[0], B3.S[3]
+	VREV32 B3.B16, B3.B16
+
+	VEOR TW.B16, B3.B16, B3.B16
+	VST1 [B3.B16], (R9)
+
+	B xtsSm4DecDone
+
+xtsSm4DecLastBlock:
+	loadOneBlock
+
+	MOVD rkSave, rk
+	EOR R13, R13
+
+decLastBlockLoop:	
+		SM4_ROUND(rk, R19, K0, K1, K2, B0, B1, B2, B3)
+		SM4_ROUND(rk, R19, K0, K1, K2, B1, B2, B3, B0)
+		SM4_ROUND(rk, R19, K0, K1, K2, B2, B3, B0, B1)
+		SM4_ROUND(rk, R19, K0, K1, K2, B3, B0, B1, B2)
+		ADD $1, R13
+		CMP $8, R13
+		BNE decLastBlockLoop
+
+	storeOneBlock
+	mul2Inline
+
+xtsSm4DecDone:
+	VST1 [TW.B16], (twPtr)
 	RET
 
 // func decryptSm4XtsGB(xk *uint32, tweak *[BlockSize]byte, dst, src []byte)