A silicone rubber composition is prepared by mixing 100 parts by weight of an alkenyl-containing organopolysiloxane having a degree of polymerization of at least 3,000 and 5 to 30 parts by weight of finely divided silica having a specific surface of at least 50 m.sup.2 /g with 0.5 to 10 parts by weight of an organopolysiloxane resin having a weight average molecular weight of 500 to 50,000, a OH group content of 0.0001 to 0.01 mol/g, and a liquefying temperature of 50.degree. to 150.degree. C., at a temperature above the liquefying temperature of the resin. The composition has high plasticity in an uncured base compound form and is effective for extrusion molding. The composition cures into silicone rubber having low hardness, good flexibility and excellent physical properties, finding a variety of applications.