Dear @YinXianpeng,
Thank you for your question.
If for your analysis you want to discard secondary neutrons produced in nuclear interactions, you have to act on the particle weight (variable WEI) not on the kinetic energy (TKI).
You can have a look at two older posts on the Forum where this topic has been discussed:
As a side comment, If you activate point-wise neutron transport in all materials because this is what you need, you should definitely remove the LOW-MAT cards and the LOW-NEUT card. In case of doubts on the settings which were finally considered for the simulation, you can always look in the output file.
Best,
Davide