An integrated flat heat pipe with new structure was fabricated to solve the problem of cooling high-power optoelectronic chip.Experiments were conducted to study the effects of filling ratio of liquid,heating power and inclination angle on the thermal performance of flat heat pipe with ultra-light porous foam metal as capillary wick,and water,acetone and ethanol as working fluid.The results show that the new structure flat heat pipe not only eliminates contact resistance between flat heat pipe and heat sink,but also improves temperature uniformity on cooling fin surfaces.When the heat power is up to 380 W,the heat flux is over 445 W/cm2,the new structure flat heat pipe still has good temperature uniformity and the thermal resistance is 0.04 K/W.In three kinds of liquid,water is the best to be used as working fluid.As the filling ratio is 30%,the flat heat pipe has the optimal heat transfer performance.The results indicate that the new structure integrated flat heat pipe with foam metal as capillary wick has good heat transfer performance and can dissipate high heat flux,which is suitable for cooling high-power optoelectronic chip.