The invention discloses a self-adaptive constant-on-time control circuit, which comprises a first transistor, a second transistor, a third transistor, a fourth transistor, a first operational amplifier, a first comparator, a first capacitive reactance unit, a first resistance unit and a switch unit. Due to the adoption of the self-adaptive constant-on-time control circuit, the problem of a traditional constant-on-time (Cot) control circuit that the working frequency is changed along with the input voltage can be solved, the quasi-steady working frequency under continuous conduction mode (CCM) status is realized, the on-off action of a power tube is reduced by reducing the working frequency under the discontinuous conduction mode (DCM) status, the on-off loss is reduced, the efficiency of a converter under a light load is improved, and the high efficiency of a full load section can be realized.