Silver nanoparticles, combine with PCF and surface enhanced Raman scattering(SERS), form SERS PCF sensor, and has been applied widely. But in practical, the PCF structure and the performance of SERS substrate have fatal influence on sensor. To exert sensor′s practical applications fully, the influence of HCPCF(hollow core PCF) and silver nanoparticles substrate structure on sensor were researched and analyzed, then the novel HCPCF and silver nano-substrate were designed to suit for SERS PCF sensor. Through numerical calculation, the air filling fraction of designed HCPCF is 56.30%. When incident wavelength is 785 nm, there is the photonic bandgap in HCPCF, and HCPCF can transmit fundamental mode, so it suits SERS sensor very well. And silver nanosphere whose radius is 38 nm, and separation distance is 0.7 nm has maximum SERS enhancement factor. The results show that whenincident wavelength is 785 nm, the designed HCPCF can supply perfect active area, and the shape, size and separation distance of silver nanoparticles have serious influence on SERS performance, moreover SERS performance rely on incident wavelength seriously.