With the development of technology, composites are used more broadly, especially at different temperature. So it is very important to research the mechanical properties of composites at different temperature. Three dimensional braided composites are new composites with high performances, in which fiber-tows are interlacing in space with multi-direction and pass through the thickness to form a no-laminated and integrated structure. However researches on the mechanical properties of three dimensional braided composites are almost at room temperature. In this paper, the tensile and bending strengths of three dimensional braided composites (TR-30s carbon fiber/epoxy) at 23 oC and 150 oC are researched respectively. The results indicate that the effect of temperature on the tensile strength and bending strength of 3D braided composites is obviously different. The average tensile strength of 3D braided composites at 150 oC is almost the same as that at 23 oC. However the average bending strength of 3D braided composites at 150 oC is mush lower than that at 23 oC. This means that the effect of temperature on different mechanical properties is different and application temperature should be taken care of when 3D braided composites bear different kind of loads.