In our previous work, we have combined the partial linearized density matrix (PLDM) approach with stochastic Lindblad dynamics to simulate polaritonic spectroscopy in lossy cavities. To include the cavity loss dynamics, we develop stochastic Lindbald dynamics, which exactly reproduce the Lindblad dynamics when averaged over an ensemble of trajectories. With simulated linear and 2D Electronic Spectra (2DES) of the polariton, we systematically investigated the influence of the light-matter coupling strength and cavity loss rate on the optical signals. In particular, we demonstrate that the polariton coherence (interpreted from the offdiagonal peak of the 2D electronic spectra) can be significantly prolonged by increasing the light-matter coupling strength, providing a theoretical verification of the po-laron decoupling effect. We now aim to generalize our approach to the collective coupling situation, where a large N of molecules are collectively coupled to a cavity mode, with the presence of various types of molecular disorders.