The Askey--Wilson integral is very important in the theory of orthogonal polynomials. Liu's integral is a generalization of the Askey--Wilson integral with many parameters. With the help of the series rearrangement method, we give the elementary proof of them. Furthermore, we establish two new Askey--Wilson type integrals in the similar way and find a generalization of a known transformation formula containing three $_{3}φ_{2}$ series.