1.添加头文件

#include <QTextCodec>

2.用QTextCodec 设置格式转换

QByteArray barr;

barr.insert(0,(char*)(pMsg->wParam));

QTextCodec *tc = QTextCodec::codecForName("GBK");

QString tmpQStr = tc->toUnicode(barr);

this->ui.send_btn->setText(tmpQStr);