My fluke 337 clamp is reading 370A on DC function ALWAYS, but the other functions work fine. Someone can help to resolve this problem? Thanks.

Check the internal fuse - usually there for amperage readings.

something damaged in input circuit

no fuse for clamp, check recall for this model and use it on known conductor that you read with another clamp to confirm fault

no fuse

what and how are you measuring?
check if your model is covered by recall
https://www.platt.com/Downloads/pdfs/recalls/Recall-Notice-for-Platt-com.pdf

1. make sure that all buttons can be pressed freely (not stuck)
2. make sure when measuring AC current that you press AC button and AC sigh is on LCD
3. make sure that jaws are closed completely
4. clamp meters use Hall effect and can only measure current flowing through ONE conductor (you cannot measure current around power cord (which has 2-3 or more conductors)
5. when in DC setting and you turn zero knob does value changes (it should)

Go on E-bay for electrical test equipment and look for growler.or go google and type in armature growler test equipment and see what you get.

check to see if you accidentally put it on manual ranging and blew a fuse ....they are unside the chassis.

try cleaning terminals. are measurements OK?

i believe theres a capture switch on there to hold previous readings,that may be on