Cu-based bulk metallic glasses (BMGs) with 5 mm in diameter were synthesized by copper mold casting. The effects of tin (Sn) addition on glass-forming ability (GFA), thermal stability of BMGs were investigated. It was found the addition of 4 at. % Sn is effective for an increase in GFA. The crystallization behaviors of Cu-based bulk metallic glasses during continuous heating are investigated mainly by differential scanning calorimeter(DSC).The results show that the characteristic temperatures(Tg,Tx and Tp) shifted to high temperature region with increasing of heating rates. The activation energies Eg, Ex and Ep, corresponding to characteristic temperatures Tg, Tx, and Tp, respectively, were obtained from Kissinger and Ozawa equations. The calculated activation energies agree well with Kissinger or Ozawa equations due to the almost invariability of the crystallization volume fraction at the characteristic temperatures for different heating rates.