The embodiment of the invention provides a hot rolled strip steel head and tail portion width control method and device. The method comprises the steps of obtaining the basic parameters of a to-be-rolled pass of to-be-rolled strip steel; obtaining the corresponding control parameters by query in a preset control database according to the basic parameters, wherein the control parameters are historical data of width control when the head and tail portions of the strip steel are rolled and comprise two or more than two control feature point data, and each control feature point data comprises a control distance and a control width; obtaining a width control curve of the to-be-rolled pass according to the control parameters; and sending the width control curve to a control system for rolling the strip steel so that the control system can control a vertical roll to roll the head or tail portion of the to-be-rolled strip steel. The problems that existing strip steel head and tail portion width control dependents on measurement equipment and the control curve precision is low are solved.