The invention provides a shift register unit, a gate drive circuit, a drive method of the gate drive circuit, and a display panel. The shift register unit comprises an input end, a reset end, an output end, an input module, a pull-down module, a pull-down control module, and an output pull-up module or an output pull-down module. Each module in the shift register unit only executes the specific voltage pull-up or pull-down function, and therefore can be formed by a single N-type TFT or a single P-type TFT. Compared with a CMOS, an LTPS and a GOA in the prior art, the shift register unit and the gate drive circuit have the advantages of being simple in structure, complete in function, and high in quality and reliability, the process is simple and easy to implement, the product cost can be reduced easily, and the application and the popularization of the CMOS, the LTPS and the GOA are promoted.