包含头文件：

#include <QWebEngineView>
#include <QWebEngineProfile>
#include <QWebEngineUrlRequestInterceptor>

继承接口类：

class requestOpt:public QWebEngineUrlRequestInterceptor{
public:
    void interceptRequest(QWebEngineUrlRequestInfo &info){
        info.setHttpHeader("key", "value");//设置请求头
    }
};

注册接口：

rq = new requestOpt;
ui->web->page()->profile()->setRequestInterceptor(rq);