Abstract: This paper aimed to study the fluidization and segregation behaviours of sawdust-straw and coal binary mixed particles during fluidization using the high-speed camera and online pressure acquisition system,further to propose an improved model to predict the related minimum fluidization velocity (U_mf).Adding a small amount of biomass particles (mass fraction below 5%) could optimize the fluidization's characteristic.However,improper fluidization (segregation and channeling) occured when mass fraction was near 10% for rough particles.With an increase of biomass mass fraction,the declined pressure drop and the enlarged U_mf are obtained.In addition,the research also shows that as the mass mixing ratio of biomass grows,the segregation degree of mixed particles rises,and the fluidization becomes unstable.