A transistor structure is provided in the present invention. The transistor structure includes: a substrate comprising a N-type well, a gate disposed on the N-type well, a spacer disposed on the gate, a first lightly doped region in the substrate below the spacer, a P-type source/drain region disposed in the substrate at two sides of the gate, a silicon cap layer covering the P-type source/drain region and the first lightly doped region and a silicide layer disposed on the silicon cap layer, and covering only a portion of the silicon cap layer.