在隧道内进行轨道网CPII作业时，由于受到场地狭小、观测视线距离隧道衬砌近和气流定向运动等因素影响,水平角易受到折光影响而产生系统误差。引用长沙至昆明客运专线黎子坪隧道轨道控制网CPII测量的实例，通过仪器自动观测、自动记录原始数据，分析长大隧道轨道控制网CPII水平角测量系统误差的产生原因和分布规律，探索减弱系统误差的措施，并提出“正反W型”观测方式的解决方案。

Due to the refraction caused by the limited space, small distance between the observation points and the tunnel lining and directional air flow, system errors often occur to horizontal angle survey of CPII control network of long tunnels. In the paper, the actual application of CPII track control network in Liziping tunnel on ChangshaKunming passengerdedicated railway is represented. The causes for and distribution rules of the system error of horizontal angle survey of CPII control network of long tunnels are analyzed on basis of automatic observation and automatic data recording, and countermeasures, such as positive and negative Wtype observation, are proposed.