We know that heat released by the system is absorbed by surrounding so Qsys=Qsurr. So Delta S should always be 0 as deltaS =q/T. but as we know that for all reaction Delta S is not 0.Plz explain it why is it not 0 always.

Dear student,
Absorption and releasing of heat is same by system and surrounding is due to the conservation of energy but the increase and decrease of entropy is not conserved that is why entropy change of the system and surrounding is different , as we know that entropy change  is the disorder ness of the molecules .
Regards