The utility model relates to a detection device for a leaky fire detector, which is particularly applicable to leakage detection projects. The utility model aims to provide a device for detecting the function of a leaky fire alarm detector, in particular a leakage current test instrument which is characterized in that a power supply (1) is connected with an oscillating circuit (2), the oscillating circuit (2) is connected with a current amplification circuit (3), the current amplification circuit (3) is connected with a power amplifier output circuit (4), and the power amplifier output circuit (4) is connected with the power supply (1). The utility model effectively realizes that the function of a leaky fire alarm detector can be detected through utilizing simulate leakage current.