${\mathrm{MAPbI}}_3$ perovskite has attracted widespread interests for developing low-cost near infrared semiconductor gain media. However, it faces the instability issue under operation conditions, which remains a critical challenge. It is found that the instability of the ${\mathrm{MAPbI}}_3$ nanoplatelet laser comes from the thermal-induced degradation progressing from the surface defects towards neighboring regions. By using ${\mathrm{PbI}}_2$ passivation, the defect-initiated degradation is significantly suppressed and the nanoplatelet degrades in a layer-by-layer way, enabling the ${\mathrm{MAPbI}}_3$ laser to sustain for 4500 s ($2.7\times {10}^7\text{pulses}$), which is nearly three times longer than that of the nanoplatelet laser without passivation. Meanwhile, the ${\mathrm{PbI}}_2$ passivated ${\mathrm{MAPbI}}_3$ nanoplatelet laser with the nanoplatelet cavity displays a maximum quality factor up to $\sim 7800$, the highest reported for all ${\mathrm{MAPbI}}_3$ nanoplatelet cavities. Furthermore, a high stability ${\mathrm{MAPbI}}_3$ nanoplatelet laser that can last for 8500 s ($5.1\times {10}^7\text{pulses}$) is demonstrated based on a dual passivation strategy, by retarding the defect-initiated degradation and surface-initiated degradation simultaneously. This work provides in-depth insights for understanding the operating degradation of perovskite lasers, and the dual passivation strategy paves the way for developing high stability near infrared semiconductor laser media.