my visa expires is that ok or will i need to get an extension of days

I think you have mixed up the validity (entry before) and duration of stay. The validity of the visa indicates the deadline for the visa holders to enter China, while the duration of stay refers to the maximum number of days visa holder is permitted to stay in China after the entry. It's ok that you exit China after your visa expires, only if your duration in China won't exceed the approved period on your visa approved by the China Embassy or consulate. At the same time, visa can't be extended, only duration of stay can be extended.