In this work, the lasing performance of a microsized single-crystal CsPbI3 triangular pyramid (MSCTP) is evaluated by measuring the lasing threshold at low temperature. The MSCTPs of well-defined facets are synthesized on a Si/SiO2 substrate with chemical vapor deposition. The MSCTP shows a spontaneous emission around 719 nm at room temperature and a stimulated emission resonant in a single Fabry-Perot mode within 148-223 K. The lasing threshold varies from 21.56 to 53.15 μJ/cm2 and presents a temperature dependence in an empirical exponential function with a characteristic temperature of 72.73 K. The temperature dependence of lasing behavior is ascribed to the competition between the exciton binding energy and thermal disturbance energy of CsPbI3. The results of this work provide us a perspective to engineer and optimize optoelectrical devices based on perovskite materials and a microsized optical cavity to investigate the light-matter interaction in quantum optics.