Abstract: A fiber coupled diode laser pumped Tm:YAP laser operating at room temperature(291 K) is reported. Using the focus-coupling system of 1∶1, the maximum output power 2.2 W is achieved at 1 928 nm, the optical-optical efficiency is 31% and the slope efficiency is 41%. The parameters which induce the change of output power, such as output coupler, operation temperature of crystal and the parameter of cavity, are analyzed. The results show that the output decreases linearly with the temperature-rise of the crystal. Because of the severe vapor absorption near 1.9 mm, the loss caused by absorption of vapor in the cavity is an important factor that decreases the laser output.