This paper studied the impact of different additives and their amount on the performances of unfired magnesia-calcia brick by detecting cold crushing strength, volume concentration, after-firing linear change, slag resistance and microstructure. The results showed that samples with Zirconia or Zircon had relatively high cold crushing strength. The sample with 4% TiO2 had the maximum volume concentration after firing. With the increase in the amount of additives, contraction occurred to all the samples, in which samples with Zircon had the smallest linear change and the most stable volume. Samples with 4% ZrO2 and Zircon had better slag resistance.