I was charged with domestic violence, finally DA dismissed it and after that I sealed my arrest record. my question is that if I have problem to get a government job? Can I get a security clearance or not?
Because your matter has been dismissed, you do not "have a record." A conviction for domestic violence can prevent you from possessing a firearm (if that is a requisite of the job), but you no longer have a conviction. Whether you can get a government job with special security clearance will depend on what precise type of job you are looking for. I would say, in most circumstances, you should have no problem.