<p><i>Mytilaria laosensis</i> is a fast-growing tropical broadleaf tree that is extensively used for wood production, forage and oil, but it grows slowly and has poor cold resistance at seedling stage. The role of rhizosphere growth-promoting bacteria in promoting plant growth and improving plant stress resistance is gradually being revealed and recognized. In this study, the seedlings were inoculated individually and in combination with Arbuscular Mycorrhizal Fungi (AMF) and an endophytic fungus (<i>Piriformospora indica</i>, Pi) under glasshouse conditions. After 60 days of inoculation, the effects on the growth and cold resistance of the seedlings were measured. The results showed that the two endophytes could form symbiotic relationship with the seedling. Compared with control, it can promote the growth of <i>M. laosensis</i> to a certain extent and improve the low temperature tolerance. Inoculation of PI increased the diameter of ground, the photosynthetic rate, and significantly decreased the contents of hydrogen peroxide (H₂O₂) and malondialdehyde (MDA). Inoculation of AMF, the plant height, root dry weight and root surface area were increased compared with the control group. Inoculation increased the number of bacteria, which was conducive to improving soil nutrient status and soil nutrient cycling. The results of this study showed that single or combined inoculation of AMF and Pi could significantly increase the biomass of <i>M. laosensis</i> and improve the cold resistance of plants by promoting plant growth and adjusting the biomass allocation strategy. The results could provide a theoretical basis for mycorrhizal growth promotion and cold-resistant enhancement of <i>M. laosensis</i>.</p>