Employing an 885 nm laser diode (LD) as the pumping source, the stable and highly efficient performance of a Cr,Nd∶YAG/GTR-KTP intracavity frequency doubled self-Q-switched miniature green laser under end-pumping is demonstrated at room temperature by using the co-doped crystal Cr,Nd∶YAG and gray tracking resistant KTP (GTR-KTP) crystal as laser active material and frequency doubling crystal respectively. The maximum average output power of 200 mW at 532 nm is achieved when the absorbed pump power is 1.65 W, and the corresponding optical-to-optical efficiency is 12.1%. When the absorbed pump power is greater than 1.15 W, the self-Q-switched green laser pulse is achieved with the energy over 8 μJ, the pulse width 8.8 ns and the peak power over 1 kW. Effects of different Nd3+ doping concentrations on the output frequency doubling power of a Cr,Nd∶YAG/GTR-KTP intracavity frequency doubled self-Q-switched miniature green laser theoretically analyzed with the rate equations. The optimized Nd3+ doping concentration is obtained to achieve efficient green laser output. Compared with those methods generating green laser under 885 nm laser pumping, the directly pumped Cr,Nd∶YAG/GTR-KTP intracavity frequency doubling self-Q-switched green laser is demonstrated to be a more ideal laser source for compressing pulse width effectively, and it provides a new method for developing highly efficient, short-pulse miniature green laser.