A respiratory monitoring system based on coreless optical fiber is successfully designed and tested. The sensor consists of coreless fiber spliced with single mode fiber on two sides to fabricate Mach-Zehnder Interferometer. The sensor coated with nanogold particles and graphene in the same way to improve the sensor's performance. The sensor was inserted into an oxygen mask tube and then put on the nose and mouth to monitor the respiratory rate for different cases. The result showed that when breathing increased, the intensity of light decreased. The light intensity of breathing at sleeping case was more than at working sport case. The sensor sensitivity was 1748 nm/RIU, and 2593 nm/RIU coated gold and coated gold & graphene. In different cases, we expect the proposed wearable breath sensor could be a valuable and dependable device for respiration rate monitoring.