1. Use the signature checking tool to check whether the signature algorithm is wrong.

2. Check whether the parameters correspond correctly (it is found that the digits of the timestamp are wrong, and the backend returns milliseconds, but it takes seconds here).

3. The corresponding value of package in the payment interface is Sign=WXPay.

4. The sign of the payment interface includes appid.

5. Payment interface, according to the signature algorithm, the last two digits need to be removed after the signature is obtained, which solves the problem of verification failure.