This paper reports the result of undercooling experiment of Pd-Ni-P alloy. Bulk metallic glass of Pd41)Ni40P19 has been formed by thermal treatment with B2O3 as fluxing. The effect of cooling rate on the undercooling behavior was studied. The surface heterogeneous nuclea-tion was reduced by embeding the sample into B2O3 melt. Thus the cooling rate used to form the glass was as low as 1 K/s at the glass transition temperature of 590 K. The temperature-time-transformation curves were calculated by using the classical homogeneous and heterogeneous nucleation theory. The critical cooling rates for the glass formation were calculated. The resuits are discussed in some detail.