To resolve the serious problem of the washing liquid leakage of dilute oil wells of Hainan the third block in Yuehai oilfield，the ZD-1 temporary plugging agent was developed，composed of 0.5% hydroxypropyl Gua，0.3% organic titanium，0.3% dodecyl dimethyl betaine，5% petroleum resin and 0.10% sodium sulfite，and the sealing performance and breaking performance of gel as well as the damage to the reservoir of the temporary plugging agent were evaluated. The results showed that the plugging rate of the temporary plugging agent to the cores with permeability of 100×10^-3—1000×10^-3 μm² was above 92%；and the gel formed by temporary plugging agent was completely broken after adding 0.02%—0.04% ammonium persulfate，and the damage rate of gel breaking liquid to permeability was only 5.23%，which was less damage to the reservoir. The agent has been applied to 8 wells and the hot washing water of the average single well was reduced by 37 m³. The average heat cleaning drainage period shortended about 3.8 days based on achieving the heat cleaning result.