A resistor-transistor-logic (RTL) circuit with GaN structure, including a GaN layer, a AlGaN barrier layer on the GaN layer, multiple p-type doped GaN capping layers on the AlGaN barrier layer, wherein parts of the p-type doped GaN capping layers in a high-voltage region and in a low-voltage region convert the underlying GaN layer into gate depletion areas, the GaN layer not covered by the p-type doped GaN capping layers in a resistor region becomes a 2DEG resistor.