The invention provides an oil displacement composition containing a betaine type surfactant and application thereof, particularly application thereof in tertiary oil recovery. The oil displacement composition is composed of the following components: 1-30 parts by weight of a composite surfactant and 0-25 parts by weight of a polymer, wherein the composite surfactant is a combination of the betaine type surfactant (I) and an non-ionic surfactant (II) in a weight ratio of (10-90):(90-10). The formula (I) is shown in the description, wherein m and n are integers from 0 to 19 but are equal to 0 asynchronously, R1 is H, C1-8 alkyl, phenyl or C1-8 alkyl phenyl, R3 is C1-8 alkyl, and R4 is C1-8 alkyl, and X is shown in the specification; and in the formula (II), R is H, C1-8 alkyl, phenyl or C1-8 alkyl phenyl, x and y are integers from 0 to 19 and are equal to 0 asynchronously, and z is an integer from 3 to 25.