Abstract Room temperature photoreflectance of molecular beam epitaxy GaAs doping superlattices was measured. Additional structures corresponding to forbidden transitions (Δn≠0) were observed at very low pump beam intensity. Experimental results show that the dominant modulation mechanism of photoreflectance of doping superlattices is different from that of bulk materials. We suggest that the photoreflectance spectrum of doping superlattices have mainly first derivative functional lineshapes, which is caused by the subband shift in doping superlattices. The experiments are well explained by this mechanism.