The effects of silica fume contents on the mechanical properties and electromagnetic transmission properties of sulphoaluminate cement were studied. The results show that with the increase of silica fume content， the compressive strength and flexural strength of sulphoaluminate cement increase first and then decrease， and the optimal content of silica fume is 10%. The electromagnetic transmission performance of sulphoaluminate cement increases with the increase of silica fume content. Compared with the sample without silica fume， the electromagnetic transmission property of silica fume-sulphoaluminate cement is improved in the range of 3.94-5.99 GHz. The peak value of electromagnetic transmittance is increased by 23.9% at most.