i have to visit PRC on S1 type.What will be the duration of my visa? how can i convert it to Z type

Moaz, usually, after you enter PRC on S1 type, you can apply for a temporary residence permit which may allow you to stay for at least one year in PRC.
If you have found a job in PRC, your employer will get you the alien employment permit and invitation letter of a duly authorized unit. After, prepare other documents containing your passport, temporary residence registration form, a half-length color photo, and the application form. Later, go to the exit and entry administration to change the S1 type to work Z type.