The application relates to a side span closure construction method. The span closure construction method comprises the steps of: splicing a side span adjacent beam section and an installed beam section, installing a stay cable corresponding to the side span adjacent beam section, and tensioning the stay cable for the first time; applying a pressure weight load to the side span adjacent beam section, maintaining the static position of a side span deck crane, and tensioning the stay cable for the second time; hoisting a side span closure beam section, putting the side span closure beam section on a transition pier to respectively regulate the axes and the elevations of the side span adjacent beam section and the side span closure beam section, adopting a jack to regulate the elevation and the planimetric position of the side span closure beam section, and performing connecting of the side span closure beam section and the side span adjacent beam section. The side span closure construction method can reduce the construction period while ensuring the deck linetype and elevation precision.