The invention discloses a cross belt sorting method, a sorting control system and a cross belt sorting system. The sorting method comprises the steps that S1, a top surface image of a sorting trolleyis received, and the state of the sorting trolley is determined; S2, when determining that only one object exists on the sorting trolley, a sorting grid corresponding to bar code information on the object and position coordinates of the sorting grid on the sorting trolley are determined; S3, virtual coordinates are converted according to the position coordinates, wherein the virtual coordinates are four vertex coordinates of a minimum enclosing rectangle of projection of the object on the sorting trolley; S4, a sorting starting point is calculated according to the virtual coordinates and the target sorting grid; and S5, when the sorting trolley reaches the sorting starting point, the sorting trolley is controlled to start sorting. According to the scheme, the position of the object on thesorting trolley is considered, the sorting starting point is accurately calculated based on the minimum enclosing rectangle of the object, the sorting precision can be effectively improved, the systemerror sorting rate is reduced to be lower than one ten thousandth from one thousandth, and the sorting reliability is greatly improved.