In this paper, porous n-GaN thin films with a pore density of 1. 51 × 1010 cm - 2 and an average pore size of 38 nm were initially prepared by UV-assisted electrochemical etching (UV-EC). Subsequently, a series of Znx Cu1 - x S composite films, with x values of 0. 0, 0. 2, 0. 4, 0. 6, 0. 8 and 1. 0, were deposited on the porous n-GaN films by water bath method. The bandgaps of the porous n-GaN/ ZnxCu1 - xS heterojunctions varied in the range from 2. 34 eV to 3. 51 eV. Hall test results demonstrate that when x values is less than 1, the Znx Cu1 - x S composite films exhibit p-type semiconductor properties. Furthermore, increasing the proportion of CuS leads to an improvement in the conductivity of the composite films. Additionally, XPS results confirm that both Cu and Zn possess a + 2 valence within the composite films. When Znx Cu1 - x S forms a heterojunction with porous n-GaN, the energy band structures of both materials interact to create a built-in electric field. This field facilitates the efficient separation of photogenerated electron-hole pairs. Finally, p-n heterojunctions UV detectors were constructed based on these heterostructures. The I-V curve results indicate that these detectors exhibit good rectification characteristics. Notably, the n-GaN/ p-Zn0. 4Cu0. 6 S detector demonstrates optimal performance. In the dark state,I + 3 V / I - 3 V is approximately 1. 78 × 105 . Under a bias voltage of - 3 V and an optical power density of 432 μW/ cm2 (ultraviolet light at 365 nm), this detector’ s photo-to-dark current ratio exceeds 103 , the rise / fall time is 0. 09 / 39. 8 ms, responsivity(R) reaches 0. 352 A/ W, the external quantum efficiency (EQE) stands at 119. 6% , and detectivity(D? ) is 3. 21 × 1012 Jones. The I-t curve results indicate that the porous n-GaN/ p-ZnxCu1 - x S heterojunctions UV detector possesses reproducible performance during the consecutive on-off optical cycling process with reproducible photocurrent response. This study offers valuable theoretical insights and a comprehensive understanding of the physical properties and performance characteristics of these novel heterostructures UV detectors.