To provide a method for producing a polyolefin by using a metallocene compound as a catalyst component.

This method is to use a catalyst system containing a metallocene catalyst component supported by an insert support and represented by the general formula R''(CpRm)(Cp'R'n)MQ2 [Cp is a cyclopentadienyl moiety: Cp' is a substituted or an unsubstituted fluorenyl ring; R'' is a structural bridge imparting the steric rigidity to the component; Rs are each independently hydrogen or a 1-20C hydrocarbyl; 0≤(m)≤4; R's are each independently a 1-20C hydrocarbyl; 0≤(n)≤8; M is a group IVB transition metal or vanadium and Qs are each a 1-20C hydrocarbyl or a halogen; the angle of the center of gravity-M-center of gravity possessed by the metallocene is within the range of 105-125° in the production of a linear low-density polyolefin in a slurry phase.