Ballistocardiography (BCG) is a technique that records the force signal caused by the ejection of blood into the arteries with each heartbeat. BCG signal can be acquired non-invasively by using polyvinylidene fluoride (PVDF) sensors integrated in a mattress or chair. In addition to being able to show cardiac rhythms, BCG signals can also be used for assessing cardiac hemodynamic changes. However, body movements, sensor displacement, etc. can easily influence the morphological characteristics of BCG signal, which makes its hemodynamic analysis difficult and even impossible. In this paper, we developed a BCG signal acquisition system using PVDF sensor. The proposed system can effectively suppress external electromagnetic interference and result in high signal-to-noise ratio. Specifically, we systematically investigated the effects of sensor position, mattress hardness and user’s posture on the stability of the BCG acquisition system, and analyzed the detection performance under apnea and the difference in gender characteristics of BCG signals. The evaluation results demonstrate that when collecting BCG signals in a lying position, it is better to use a hard mattress (such as a wooden bed) and place the sensor directly below the hear. When the above conditions are met, the collected BCG signals waveform is the optimal; the H, J, and K waves are significant and have a strong rhythm, which is conducive to improving the accuracy of hemodynamic analysis.