In this paper, an unconstrained cardiorespiratory system for monitoring of ECG and respiration during sleep is presented. A novel active dry ECG electrode, which based on the conductive flexible and stretchable Ag NWs/PDMS composite material is designed to acquire the electrocardiographic potentials through the cloth. Meanwhile, a membrane pressure sensor is applied to obtain the respiratory signal, which can avoid the intervention in the sleep process. Combining the novel active ECG electrode and the membrane pressure sensor, the followed signal acquisition circuit is designed to monitor the ECG and respiratory signals simultaneously without fixing any external sensor to the human body. To verify the performance of the proposed system, a comprehensive test protocol is presented. Firstly, we characterized the electrical properties and the signal sensing capability of the proposed sensor. Furthermore, the performance of the entire system is assessed to verify the effects caused by different clothing materials and sleep postures to the ECG signal and the respiratory signal acquisition. The average Pearson correlation coefficient of the RR interval that extracted from the ECG signal obtained by the proposed system and the commercial PSG device can reach over 0.9 of different clothes and postures. As for the respiration acquisition, the accuracy of the respiration rate in different postures can reach 95% during the 2 hours monitoring process. The experimental results are promising, which demonstrate that the proposed system can achieve favorable signal quality and satisfy the basic requirements of the cardiorespiratory monitoring during sleep. Moreover, the proposed system can be extended to the office environment to monitor the health status of the individual.