The present invention discloses a isolation transmission circuit used for transferring clock signal and data signal between a first equipment and a second equipment, wherein the isolation transmission circuit comprises a small signal transformer provided with one time side and secondary side; the clock driver output comes from clock signal to one time side of the first equipment; data driver output comes from data signal to secondary side of the second equipment; on the one time side, a first reference signal generator generates the first reference signal proportional with the clock signal; adata output comparator removes clock signal from transfer signal mixed with clock signal and data signal of a small signal transformer according to the first reference signal to output the data signal to the first equipment; on the secondary side, a second reference signal generator generates a second reference signal proportional with data signal; the clock output comparator removes data signal from transfer signal mixed with clock signal and data signal of a small signal transformer according to the second reference signal to output clock signal to the second equipment.