Recent observations and theories suggest that GeV cosmic-rays are dominated by SNRs interacting with molecular clouds while TeV cosmic-ray may have significant contributions from other sources, such as PWNes. Now LHAASO-WCDA have enough significance with E=1 TeV for SNR G150.3+4.5. Its spatial distribution and extension are consistent with that of the radio and the GeV band revealed by Fermi, and the extension of about 1.5 degrees. A source inside SNR G150.3+4.5 is detected by LHAASO-KM2A with a total significance of 9.4 sigma for E $>$ 25 TeV. The best-fit source location is (R.A., Dec.)= $(66.63^{\circ}\pm 0.11^{\circ}, 54.63^{\circ} \pm 0.05^{\circ})$, and the Gaussian extension is $0.32^{\circ} \pm 0.06^{\circ}$. It is spatially coincident with 4FGL J0426.5+5434, which has a soft GeV spectrum reminiscent of a pulsar. The broadband nonthermal emission can be interpreted as a contribution of a supernova remnant and a PWNe or high density molecular clouds interacting with high energy proton.