The plasma cavity formed by metal ion droplets and liquid polydimethylsiloxane (PDMS) as a novel surface-enhanced Raman (SERS) substrate integrates plasmonic nanoparticles into optical devices, improving SERS detection, practicality and reliability, however, there are few studies on their optimal growth conditions compared to other substrates. Here, we used the banned veterinary drug Malachite Green (MG) as a probe molecule to examine the characteristics of the plasma chamber under different growth conditions, including growth temperature and metal ion concentration, to study the optimal growth conditions of the plasma chamber. When the aqueous metal ion solution is dropped onto the mutually incompatible liquid PDMS, a spherical cavity with an opening is spontaneously formed by the combination of surface tension and gravity. At the same time, the metal ions diffuse into the uncured PDMS and react with the residual Si-H groups. The metal ions are gradually reduced to metal nanoparticles, and gradually accumulate on the surface of the cavity as the PDMS solidifies, eventually forming a plasma chamber. It can not only be used as an angle reflector to confine the incident light in the cavity, but also can be used as a nano-scale photon source to scatter the absorbed light into the cavity. These two functions work together to further enhance the Raman enhancement of MG based on the original enhancement of the substrate. The higher growth temperature accelerates the growth of the PDMS while accelerating the growth of the metal ions, so that the growth process of the metal nanoparticles is terminated prematurely. The higher the ion concentration, the larger the metal ion particles formed. However, the particle diameter is too large, the number of hot spots on the surface of the plasma chamber will decrease, and the Raman enhancement of MG will be weakened. Therefore, there must be optimized plasma chamber preparation conditions to maximize the enhancement of the substrate to MG. We set the growth temperature of 15, 20, 25, 30 ℃ and the ion concentration of 0.05, 0.5, 5, 50 μg·mL-1. The results show that the plasma chamber achieves the best Raman enhancement of MG at a temperature of 25 ℃ and 0.5 μg·mL-1 growth conditions. The optimization of plasma chamber growth conditions can lay a foundation for improving the SERS enhancement effect of this type of substrate and repeatable preparation.