Disclosed is an apparatus for measuring ac magnetization at mixture frequency. The apparatus includes an ac generating unit for generating at least a first current with a frequency f1 and a second current with a frequency f2. The apparatus further includes a co-axial solenoid unit, driven by the first and second ac currents, to generate a first magnetic field and a second magnetic field. A pick-up solenoid is for disposing sample for detecting an ac magnetization of the sample and multiple frequency-component signals corresponding to various frequency combinations of f1 and f2 are output. The apparatus further includes a signal processing circuit for receiving the frequency-component signals, where the signal processing circuit obtains the ac magnetization of the sample at a target frequency of (γTf1+βTf2), which γT and βT are positive integers and the frequency f1 and the frequency f2 are two different frequencies.