The invention provides a control method for automatic roll changing of a finishing mill unit, and belongs to the field of automatic control technology. Under the circumstance of not changing the structure of on-site mechanical equipment, the control method has the advantages that one-key type automatic roll changing is realized, roll shifting return-to-zero control technology and upper roll system pad shifting movement timing sequence control are resigned, a step pad hydraulic mechanism speed control program and a roll changing buggy position calibrating program are developed independently, equipment movement speed and position control precision are effectively improved, and the automatic roll changing work efficiency of the finishing mill unit is remarkably improved; the situations that not all machines need roll changing in actual production and roll changing is urgently needed under the abnormal condition are taken into full consideration, control technology and step sequence movement which frequently cause automatic roll changing break-off in the roll changing procedure are optimized, the occurrence probability of the roll changing delay condition caused by the on-site equipment confirmation link and detection equipment abnormity is reduced, the operation difficulty of operators is lowered, the labor intensity of the operators is relieved, the automated control level of finishing mill roll changing is greatly improved, roll changing time is effectively shortened, and meanwhile the annual production capacity of a 1580 hot continuous rolling mill is remarkably enhanced.