For　the　first　time,　the　SHG　efficiency　of　RBBF　crystal　in　type-I　and　type-II　phase　matching　has　been　simulated.　RBBF　crystal　is　pumped　by　the　fundamental　radiation　of　a　Q-switched　Nd:YAG　laser　with　the　wavelength　of　1064nm　and　the　shape　of　plane　wave　or　Gaussian　beam.　When　the　pumped　radiation　is　of　plane　wave,　the　conversion　efficiency　of　RBBF　in　type-I　and　type-II　could　be　as　high　as　100%　and　78%.　When　the　pumped　radiation　is　of　Gaussian　beam,　the　conversion　efficiency　shows　a　monotonically　increasing　trend　in　the　type-I　phase　matching,　and　in　the　type-II　phase　matching　the　conversion　efficiency　varies　periodically.