【Background】The western flower thrips, Frankliniella occidentals (Pergande), is one of the invasive insect pests in China, and is resistant to many insecticides. In order to develop alternative methdos of control, we tested the virulence of eight isolates, of the insect pathogen Beauveria bassiana namely, BbKM030716, BbCG051229， BbJS080625， BbQJ031121, BbXW060615, BbSM090521, BbYY090613 and BbMZ051230 to F.occidentals was assessed in the laboratory. 【Method】Virulence was characterised by a standard timedosemortality model．【Result】The lethal concentration LC50 values vaired with time after inoculation and the lethal dose LT50 values varied with concentration. The virulence index for different isolates of B.bassiana against western flower thrips was [JP2]1.[KG-*8]43， 0.[KG-*8]87， 0.[KG-*8]93， 0.[KG-*8]98， 1.[KG-*8]23， 0.[KG-*8]92， 1.[KG-*8]07 and 0.[KG-*8]86 respectively． The corrected mortality incresed from 44.[KG-*8]13% to 98.[KG-*8]49%， 12.[KG-*8]63% to 78.[KG-*8]90%， 30.[KG-*8]36% to 96.[KG-*8]92%， 51.[KG-*8]36% to 98.[KG-*8]74%， 26.[KG-*8]14% to 98.[KG-*8]59%， 7.[KG-*8]27% to 78.[KG-*8]71%， 49.[KG-*8]06% to 98.[KG-*8]74%， and 27.[KG-*8]67 to 87.[KG-*8]36%[JP]， by inoculation of the dose of 1.[KG-*8]25×104~1.[KG-*8]25×108 conidia·mL-1 over 10 consecutive days． The mortality of adult thrips was dose and timedependent. Value of LT50 was decreased with the increase of the concentration.【Conclusion and significance】The isolates of BbKM030716， BbJS080625， BbQJ031121 and BbXW060615 were the most virulent isolates against F.occidentalis and show promsie as biological control agents.