The effects of the position and size of local defects without diffusion function on patterns of twodimensional random neural network were investigated by using the HodgkinHuxley model. The result shows that the spiral wave becomes more scattered when the size of defect gets bigger, significantly near to the center of the spiral waves, which means the defect impact is correlated with the defect size positively. Furthermore, it is found that the drift phenomenon of spiral wave is induced by defect in weakly coupled neural network. Study on the behavior of spatiotemporal patterns with the coexistence of channel noise and defect shows that the new wave source is made by the effect of noise. Finally, the physical mechanisms for these phenomena were briefly discussed by analyzing the discharge frequency and the mean membrane voltage of neurons.