Using a first-principle pseudopotential plane-wave method, the energetic, geometrical and electronic structures of point defects are calculated for B2-RuAl intermetallic compound. Based on the calculation and comparison of the formation heat and formation energy for several kinds of point defective structures, the type and the geometrical configuration of point defects in B2-RuAl intermetallic compound are analyzed and forecasted. Results show that the major point defects in B2-RuAl intermetallic compound are vacancy or anti-site in the Ru sublattice, i.e., Ru vacancy and Al anti-site, but mainly Ru anti-site defect in rich-Ru alloy, and mostly Al anti-site defect in rich-Al alloy. These point defects emerge in the form of Ru-Ru double vacancy or Al-Al double anti-site configurations, namely, there are two vacancies or two Al atoms in the Ru sublattice. And they would be in the most stable structure when the double vacancies at Ru sites were in the first nearest neighborhood, or when the double Al atoms at Ru sites were in the third nearest neighborhood. In addition, the influences of above point defects on Cauchy pressre parameter(C12-C44)of B2-RuAl and NiAl were also compared. It is found that the decreasing of C12-C44 caused by point defects in RuAl is smaller than that in NiAl, so that the ductility of RuAl metallic compound with point defects at room temperature is better than NiAl.