A siloxane powder composition which can impart improved lubricity character to a thermoplastic resin is disclosed, said composition being prepared by mixing(A) 100 parts by weight of a liquid polydiorganosiloxane and(B) 40 to 200 parts by weight of a silica powder that has a specific surface of at least 50 m.sup.2 /g using sufficient shear to prepare a powder in which the surface of component (B) is coated with component (A), and then mixing this powder with(C) 10 to 50 parts by weight of a polyorganosiloxane resin which is a solid at room temperature, said resin consisting essentially of (R.sub.3 SiO.sub.1/2) siloxane units and (SiO.sub.2) siloxane units in the molar ratio of 1:4 to 1:1,where R is selected from the group consisting of alkyl radicals and phenyl radical.