We demonstrate significant improvement of hole injection and transporting in organic light-emitting diodes (OLEDs) by utilizing gradient doping in hole transporting layer (HTL). An ultrahigh doping concentration at the anode side to enhance the hole injection, whereas low doping concentration close to emission layer to avoid possible quenching of excitons. A plural HTL with concentration step are introduced in between to smooth the hole transporting. Compared to conventional hole injection technologies, the gradient doping significantly enhances the current density and luminance of the OLED.