Yb:CaGdAlO4(called CALGO) is a promising new laser gain material which possess several important advantages. The crystal structure of CALGO is tetragonal. When it is pumped at 979nm under pi configuration, we can get broad emission spectra from 994nm to 1050nm in theta configuration. This implies a very small quantum defect (down to 1.5%) and gives a good expectation of obtaining ultra-short pulse. Its thermal conductivity is also high: k=6.7W/m/K, which means it can be used for high power laser applications.