Path　planning　is　a　key　part　of　ensuring　that　smart　vehicles　are　safe　and　fast　to　reach　their　destination.　Currently,　global　path　planning　mainly　uses　Astar　algorithm　for　search　planning.　Astar　algorithm　is　a　heuristic　search　algorithm,　which　has　been　widely　used　in　path　planning,　but　it　has　many　disadvantages,　such　as:　low　search　efficiency,　poor　real-time　performance,　and　there　are　no　constraints　in　search.　In　view　of　the　shortcomings　of　Astar　algorithm,　this　paper　presents　Bidirectional　search-Binary　tree　Astar　algorithm(BBAstar),　BB-Astar　algorithm　has　following　improvements:　First,　binary　tree　data　structure　is　added　to　the　open　table　of　Astar　algorithm　to　optimize　the　efficiency　of　the　algorithm;　Second,　use　bidirectional　search　strategy　to　further　improve　the　efficiency　of　the　algorithm;　Thirdly,　two　kinds　of　constraint　conditions,　which　must　pass　through　a　certain　node　and　a　certain　road　section,　are　set　in　the　algorithm　to　make　the　algorithm　more　practical.　Simulation　results　show　that　the　search　efficiency　of　the　BB-Astar　algorithm　is　better　than　classic　Astar　algorithm,　and　the　search　with　constraints　can　be　completed.