The efficient extraction of targets from complex environment is the key to analyze explosive traces and soil pollution. In recent years, the focus of Raman detection of trace organic pollutants is to create hotspots for amplifying Raman signals. This paper demonstrated the combination of gold nanostars (AuNS) fabricated by seed mediated growth method with three-dimensional opal photonic crystals for SERS trace detection. As a result, the obtained composite structures show excellent SERS activity with low detection limits of 540 ppt to 3-Phenoxybenzoic acid (3-PBA) (0.54 ppb) and fast detection time of 10 s. The utility of the composite structures was demonstrated by directly detecting soil pollution in water with a simple dropping. Additionally, the local electromagnetic field distribution for the photonic crystals and AuNS composite substrates were calculated by the finite difference time domain (FDTD) method. Overall, this work provides a simple, rapid, and sensitive way to monitor the insecticides in the soil and other side.