Abstract: To solve the problems of the fire separation distance between new buildings, retrofit buildings and existing buildings in historical and cultural blocks, 3 typical building was selected to simulate the highest heat radiation intensity of adjacent building by FDS. The fire separation distance was 2.0,2.5,4.0,6.0 m. The results showed that when the spacing is 4.0 m, the radiant heat flux can reach or close to the ignite radiant heat flux of flammable furniture. When the spacing is 6.0 m, the radiant heat flux is lower than the ignite radiant heat flux of flammable furniture. On this basis, combined with the analysis of relevant code provisions and the requirements of the practical project, different technical measures such as no opening and staggered opening on the outer wall, setting fire doors and windows and / or setting sprinkler system are considered respectively, and correspondingly the fire separation requirements between new buildings, new buildings and reconstructed buildings, and existing buildings in historical and cultural blocks are suggested.

Key words: historical and cultural blocks, restoration and reconstruction, building fire protection, fire separation distance