Grotto stability and visitor safety are threatened by the development of dangerous rock mass. Monitoring and analysis of the deformation characteristics of dangerous rock mass in grottoes play a crucial role in the stability assessment of rock mass. Considering the North Grotto Temple in Qingyang, Gansu Province, as the example, Global Navigation Satellite System deformation monitoring, joint meter, and noncontact fissure monitoring techniques were applied for analysis of the deformation characteristics of dangerous rock mass in three scales, namely, the regional geological body, cliff body, and key blocks of the North Grotto Temple. During the monitoring period, the displacement of the upper regional geological body presented a sudden change, with a settlement of 5.2 mm after continuous rainfall, the displacement of the central bedrock recovered gradually after a slow growth, and the deformation was within ±1 mm. The deformation at the bottom of tectonic fissures in cliff increased in fluctuating form, with the highest value in January—February of the following year. With decreasing temperature, the deformation rate in the middle of the fissure was quicker than that at the bottom. The deformation of superficial fissures in cave 32 fluctuated near 0 mm in the range of ±2 mm. Deformation of the regional geological body was highly correlated with rainfall, and that of the cliff was negatively correlated with temperature; moreover, the deformation of key blocks was also susceptible to temperature, humidity, and human disturbance. Current deformations of the rock masses at the three scales varied within a small range, with little influence on each other and no synergy. This study can provide reference data for the stability assessment and predictive analysis of the North Grotto Temple.