in my pdk，the nmos device model name is nch，but monte carlo simulation model name is nch_mis，so when do mc simulation，first i need to generate the netlist，then i should convert the model name nch to nch_mis using skill func( the skill func already exist)，the problem is i don't know how to insert the convert function.
monteRun() command will automaticly regenerate the netlist，so，i don't know when i can modify the netlist，and then continue mc simulation
If it's the PDK I think you're using, there will be a separate symbol for monte carlo than for conventional simulation. This is a rather strange design choice by the creators of the PDK, but what most people do is to use the "_mis" or "_mac" (depends on which version it is) flavour of the devices all the time - that way you don't have to keep changing them back and forth.
If you do that, then it will work in all simulations, with no need to hack anything. You should be able to do a find and replace to change the devices. Or a bit of SKILL code.