Objective Activated clotting time（ACT） and fibrinogen（Fbg）are regularly monitored during Coronary Artery Bypass Graft（CABG）. We got the results of ACT and CR by using Sonoclot coagulation analyzer（SCA）to canpare with conventional ACT test（C-ACT）and Fbg，and discussed the differences among the various methods of monitoring ACT and CR duning CABG. Methods 30 patients undergoing CABG were divided into 2 groups, off-pump CABG group（OP, n=18）and cardio-pulmonary bypass CABG group（CPB, n=12）. Blood samples were collected through C-line to dertermine the value of C-ACT and sonACT, kACT, aiACT, sonCR, kCR and aiCR after induction（T0）,5 minutes after presenting heparin（0.8 mg/kg in OP group, 1.0 mg/kg in CPB group）（T1）, 5 minutes after adding heparin（added to 1.5 mg/kg in OP group, 3.0 mg/kg in CPB group）（T2）, 5 minutes after heparin neutralization with protamine（T3）. Results ① At point T0, the baseline of the three ACT of SCA all correlates with C mg/kgACT, the correlating equations are y=83.15+0.37×（R=0.438, P<0.05）, y=71.33+0.43×（R=0.509，P<0.01）, y=56.19+0.78×（R=0.790，P< 0.01）, respectively. And the CRs all correlates with Fbg, the correlating equations are y=1.16+0.09×（R=0.821，P<0.001）; y=1.11＋0.09×（R=0.773, P<0.001）; y=1.50+0.06×（R=0.882，P<0.001）, respectively. ② There is significant difference between T0 and T3 on the results of C-ACT, P<0.01, but not the SCA results. ③ When the dose of heparin is low of 0.8mg/kg or1.0mg/kg, the percent of the patients whose C-ACT higher than 300 seconds is 39% or 83%, and whose sonACT and kACT higher than 300 seconds is 55% or more than 92%. The percent of the decrement of CR is 74%~76% or 76%~83%. Conclusion ① The comparation of the correlation: aiACT >kACT >SonACT，aiCR >sonCR >kCR, So both of aiACT and aiCR are more accruate than the others. ② After heparin neutralization, the recovery of the SCA results are better than C-ACT. ③ SCA is more sensitive than C-ACT when the dose of heparin is low such as 0.8 mg/kg-1.0 mg/kg.