A diode-end-pumped self-Q-switched mid-infrared laser was demonstrated with Er3+, Pr3+ co-doped CaF2 crystal for, to the best of our knowledge, the first time. Maximum average output power of 262 mW was achieved and the corresponding slope efficiency was 14.9%. Stable self-Q-switched laser pulses as short as 718 ns were obtained with a repetition rate of 52.63 kHz at the center wavelength of 2803.7 nm. This highly compact nanosecond laser using a 3 at. % Er3+ and 0.03 at. % Pr3+ co-doped CaF2 crystal is free from any active or passive modulators in cavity, potentially promising for a micro and integrated diode-pumped mid-infrared laser system.