This experiment explored the technology of measuring the surface tension of viscous liquids using the suspension drop method．By using micro injection control technology and combined with continuous image acquisition methods for dynamic processes，the droplet morphologies at different liquid volumes were obtained．The surface tension coefficient of silicone oil was calculated using the critical state image at the equilibrium case between droplet surface tension and gravity．Compared with the standard value，the relative error of the measurement data is about 4%．