With the echo data of Zhengzhou 714CD Doppler radar from May to August from 2002 to 2004, the severe convective echoes that move towards Zhengzhou within 90km (echo intensity≥50dBz, echo height≥9km) and produced near Zhengzhou are investigated. The relationship between thunderstorm outflow boundary and severe convective weather in Zhengzhou, and the impact of strong echoes without outflow boundary on weather of Zhengzhou are analyzed.