I have flashed my ASUS Z270M-Plus mainboard with ASUS Z370P BIOS image after replacing some modules so that it can support 8700 CPU, and all devices works fine,but there's a problem that it can not resume from S3 state.
When I click the power button in S3 state, the FAN and the HDD spins up but no display output and keyboard no function. . .
Can anybody help me?

Did you modify ACPI tables? If so, that may be why, could be bad mod, or due to the modifications it's something you have to live with for that CPU. Best to ask in the BIOS mod thread where you learned steps on the mod, they may know what caused it.

No modification to the ACPI table of Z370 bios, I don't know which part of the table is responsible to S3 resume process.

Are you sure, I mean when you replaced modules, were they from some other persons mod? if yes, then could be culprit. I am not sure either, but I think it's ACPI related stuff.

I am sure, the modules mod are just VBIOS and LAN related.
Thank you anyway.

vBIOS and LAN modules are not related at all to making your BIOS/board compatible with the 8700 CPU. Many modules are edited and modified, like you see in this thread, and this is just an after the fact mod for HT - [GUIDE] Fixing HT for Coffee Lake CPUs on Skylake and Kaby Lake motherboards (Z170, Z270)
For original compatibility to be added ME is changed/modified, Microcode's added, and PCIE modules patched - [GUIDE] Coffee Lake CPUs on Skylake and Kaby Lake motherboards

If the first link to fix HT was done, then ACPI modules edited for sure. See here, in first thread I linked, they also discussing Sleep and ACPI - [GUIDE] Fixing HT for Coffee Lake CPUs on Skylake and Kaby Lake motherboards (Z170, Z270)