Abstract: In view of unable to make full use of the iron rich rhodochrosite，the preparation process of manganese sulfate with the rhodochrosite has been investigated.Problems on slurry viscosity and difficult neutralization reaction in the process have been focused on.The optimal process conditions were obtained as follows: leaching temperature was 90 ℃，mass ratio of liquid to solid was 5.5∶1，mass ratio of sulphuric acid to rhodochrosite was 0.69∶1，leaching time was 2 h，and filtering temperature was about 70 ℃.Under these conditions，the preparation process could be carried out smoothly，total yield of Mn would be increased by 5%~8% and the filtering operation time would be shortened to 1/3 compared with the traditional technology.

Key words: iron rich rhodochrosite, utilization coefficient of total manganese, filtering time