Abstract: Blackheart malleable cast iron has generally been making of the raw material containing sulphur less than 0.15%. Authors investigated the possibility of producing superior grade castings by using the raw material containing sulphur 0.2~0.4%, and have already obtained primary success. Now, castings reaching the grade of RI37-12 are estimated more than 80%. Several points of experience obtained are summarized as follows: 1. To regulate silicon and manganese contents of molten iron according to the empirical formulas Si%=2S%+1.0%; Mn%=2s%+0.2%. Carbon content should be controlled about 2.3~2.5%, at the same time keep C%+Si%≈3.9%. 2. High pouring and tapping temperature is required, and the gating, running and feeding technique must be suitable. The moisture content of mould sand must be less than 5%, and the green permeability of mould sand must be over 60 A.F.A.. Then the defects of pinholes and sub-surface blowholes in castings will be greatly eliminated under such conditions. 3. It is very important to use low-temperature high-speed method of heat treatment in the first stage for the raw castings. The mechanical properties of castings decrease rapidly if the annealing temperature the inferior mechanical properties of the castings will result. The mechanical properties of castings will be greatly improved by decreasing the casting defects according to the experience above mentioned.