The invention provides a continuous tunable single-frequency ti sapphire laser based on locking of an electro-optical etalon of an internal cavity. The laser comprises a pumping source, a ti sapphire crystal, a laser resonator, an optical isolator, a double-refraction filter plate, the electro-optical etalon, a vibrating mirror motor, piezoelectric ceramics, a beam splitting mirror, a photoelectric detector, a servo controller, a high-voltage driver and a signal generator; the light field in the cavity is modulated by utilizing a photoelectric effect of the electro-optical etalon, and the photoelectric detector detects and extracts error signals; and the electro-optical etalon is mounted on the vibrating mirror motor, the vibrating mirror motor is used to control the angle of the electro-optical etalon, and the electro-optical etalon is locked in real time. According to the invention, the light field in the cavity is modulated by utilizing the photoelectric effect of the electro-optical etalon, the photoelectric detector detects and extracts error signals and enables the vibrating mirror motor to control the angle of the electro-optical etalon, the transmission peak of the etalon is locked in the laser oscillation frequency in real time, and the cavity length of the laser resonant cavity is changed to realize continuous tuning of the laser frequency.