The invention provides a fire-flooding well self-degradable temporary plugging agent and a preparation method and an application thereof. By metering the total weight of the self-degradable temporaryplugging agent is 100%, the raw materials for preparing the self-degradable temporary plugging agent include: 0.3-0.8% of a main agent; 0.01-0.05% of a cross-linking agent; 0.5-2% of oil-solubility resin; 0.2-0.6% of fiber particles; 0.02-0.1% of a heat stabilizer; 0.1-0.5% of a fungicide; 0.2-0.6% of a cleanup additive; 1-3% of a fluid loss reducer; 0.001-0.004% of a slow release gel breaker, andthe balance of water. The fire-flooding well self-degradable temporary plugging agent has the characteristics of good pumping property, temperature resistance, simple preparation, and low cost, and the gel breaking time is adjustable, the sealing ability is strong, and the self-degradable temporary plugging agent is suitable for wide oil reservoir types, and is not easy to pollute the stratum andcan enter a deep part of the stratum, which can effectively solve the production problem of large gas production amount of the fire-flooding wells.