Abstract: With the increasing complexity of the electromagnetic environment and the gradual improvement of technologies such as stealth and radar countermeasures, the role of radar weak target detection and tracking technology in modern military fields such as anti-missile, early warning, defense, and remote sensing is becoming increasingly prominent. For the detection and tracking of weak targets in complex environments, due to the similar motion states and small size of the targets, they are susceptible to noise and clutter interference, resulting in low signal-to-noise ratio of the targets, making them difficult to detect and track. This paper proposes a single-illuminator single-receiver multi-Bernoulli track before detection (SISR-MB-TBD) algorithm based on a single external radiation source and a single receiving station (single illuminator single receiver) passive coherent location (PCL) system to address the problem of low detection rate of weak targets. Firstly, by combining dynamic update mechanism and probability evaluation method, a new target search mechanism based on multi-Bernoulli components is constructed to obtain the new location of the target; Then, combining the theory of multi-Bernoulli random finite sets with Gaussian particle filtering theory, utilizing the measurement information from a single external radiation source and a single receiving station to achieve target state prediction and measurement updates; Finally, based on the concept of energy accumulation likelihood ratio proposed in the update step, the likelihood function of the target with respect to particles is obtained and passed on to the next moment to complete inter frame accumulation, achieving the detection of weak targets. The simulation results show that the proposed algorithm effectively improves the detection rate of weak targets while reducing target state estimation errors and potential errors, and has good engineering application prospects.