We investigate the impact of threading dislocation density on the reliability of 1.3 lm InAs quantum dot lasers epitaxially grown on Si. A reduction in the threading dislocation density from 2.8108 cm2 to 7.3106 cm2 has improved the laser lifetime by about five orders of magnitude when aged continuous-wave near room temperature (35 C). We have achieved extrapolated lifetimes (time to double initial threshold) more than 10 106 h. An accelerated laser aging test at an elevated temperature (60 C) reveals that p-modulation doped quantum dot lasers on Si retain superior reliability over unintentionally doped ones. These results suggest that epitaxially grown quantum dot lasers could be a viable approach to realize a reliable, scalable, and efficient light source on Si.