Abstract: The echolocation calls of Coelops frithi were recorded during free flight using an ultrasonic detector U30, and were analyzed using the software Batsound 3.0. Our results showed that C. frithi emitted high frequency (145.4±10.9 kHz), broad bandwidth (62.6±9.2 kHz), and short (1.67±0.4 ms) frequency-modulated (FM) calls with 2 harmonics, which suggested polymorphic echolocation calls in Hipposideridae because other hipposiderid species emitted constant frequency (CF) calls. The analysis of the cranial measurements of C. frithi indicated that it was a nasal emitter like other hipposiderids, which suggested the single emitting form in this family. We considered that C. frithi emitted FM calls mainly due to the selection pressure of evolution and the adaptability between wing morphology and echolocation calls.