The invention provides a mother-son antitheft lock unlocked through magnetic codes. The mother-son antitheft lock comprises a lock cylinder body and a key body. The lock cylinder body comprises a fixed outer lock cylinder barrel, a first inner lock cylinder barrel and a second inner lock cylinder barrel. An elastic ball for restraining rotation is arranged between the first inner lock cylinder barrel and the outer lock cylinder barrel, and a mother lock is jointly formed; and a limiting mechanism for restraining rotation is arranged between the second inner lock cylinder barrel and the outer lock cylinder barrel, and a son lock is jointly formed. The key body comprises a mother key, a son key and a restraint component arranged between the mother key and the son key, the mother key coaxially sleeves the outer portion of the son key, the son key is set to have the contraction state and the stretching-out state capable of being switched, and in the initial state, the restraint component restrains the son key into the contraction state. The mother key and mother lock are matched to rotate for triggering so that the son key can be switched to the stretching-out state, and the son key inthe stretching-out state releases rotation restraint of the limiting mechanism between the second inner lock cylinder barrel and the outer lock cylinder barrel through magnetic attraction/repelling.