I have no job for long months, and I stayed thailand for long months by go out and into for many times.

I found there are occupation writting space in thai visa,

so how should I write the occupation space?

maybe no job? or I should write some job to get visa?

up to u.You can write anything on visa application.Either Unemployed or employed.But better to write Employed.They don't care and will not ask you about where u employed

I have no job for long months, and I stayed thailand for long months by go out and into for many times.

I found there are occupation writting space in thai visa,

so how should I write the occupation space?

maybe no job? or I should write some job to get visa?

You can only be applying for a tourist visa, so just use your last real job description.