In this work, a new method to fabricate high-purity Ti3AlC2 powder by pressureless sintering (PLS) was reported through adding a little amount of B2O3 as a low-temperature aid. The elemental Ti, Al, and active carbon powders were used as raw materials with the molar ratio of 3 : 1.2 : 2. The effect of sintering temperature on the purity of Ti3AlC2 was investigated at the range of 800°C to 1400°C. The results showed that high-purity Ti3AlC2 powders, in which almost no TiC phase could be found, were stably fabricated by pressureless synthesis at 1400°C for 5 mins in flow Ar atmosphere. The roles of B2O3 addition were discussed in the paper.