The invention discloses a self-calibration method and a system for a magnetostriction liquid level sensor. The method is characterized in that the method comprises the following steps of: generating a current pulse by a pulse processing module, transmitting the current pulse in a waveguide wire, contacting with a magnet in a floater, generating a torsional wave, measuring time T1 that the torsional wave is upwards transmitted to the pulse processing module and time T2 that the torsional wave is downwards transmitted to a terminal of the waveguide wire and is reflected to the pulse processing module by a singlechip; utilizing length H of a feeler lever and the time T1 and the time T2 by the singlechip, according to a formula: V=2H / (T1+T2), and obtaining a real-time velocity of propagationV; utilizing the real-time velocity of propagation V, the length H of the feeler lever and the time T1, according to a formula: h=H-V*T1, and obtaining a current liquid level height h. The invention has the advantages that: temperature influence on the waveguide wire and a crystal oscillator can be automatically removed, more accurate liquid level signals are transmitted in real time to a controlsystem of the magnetostriction liquid level sensor, and accurate measurement of a liquid level can be achieved.