In this paper, we propose a method to eliminate the baseline wander for ECG based on waveform morphology analysis. This method uses the ascending slope tracing waves to approximate the baseline wander in ECG and subtracts these waves from the original ECG to eliminate the baseline wander. This ascending slope tracing waves was developed for efficient enhancement of slope inverting points and sudden slope changing points. This method has been applied to MIT/BIH database to verify its efficacy and validity in practical applications.