Abstract: Combined with the monitoring example of the open-cut section of a cable tunnel for Houde Substation in Guangzhou,the monitoring safety design and instrument layout were introduced in the system of steel sheet pile and steel struts structure.The monitoring frequency,alertness values and reports etc were presented.According to the analysis and forecast of monitoring data especially the unusual ones,monitoring result was researched to adopt countermeasures,and safety precautions were adopted in time,hence the safety of the field and environment could be ensured.