The general measurement method of transmission matrices based on phase-only modulation is proposed and the experimental setup is established for the measurement of the transmission matrices. The identity matrix modulation and the Hadamard matrix modulation are employed respectively in the measurement of the transmission matrices, and the focusing of light waves through scattering media is realized. The experimental results show that the focusing point intensity of the transmission matrix measured based on the identity matrix is 19 times the background light intensity, while the focusing point intensity of the transmission matrix measured based on the Hadamard matrix is 16 times the background light intensity.