Disclosed is a microporous composite film having a coating layer formed on at least one surface of a microporous polyolefin film, wherein the coating layer simultaneously includes a high thermostable polymer resin and inorganic particles. More specifically, the present invention relates to a microporous composite film in which an area shrinkage at 170° C. for 1 hr is 10% or less; a tensile modulus in each of a machine direction and a transverse direction at 130° C. is 0.5 MPa to 7.0 MPa; a ratio between permeability of a microporous composite film (CCSp) and permeability of a microporous polyolefin film (Sp) is 1.1≦CCSp/Sp≦3.5; and a permeability of the microporous composite film is 450 sec or less.