Single-photon　counting　technology　has　been　used　extensively　in　testing　due　to　its　powerful　quantitative　performance　for　ultraweak　luminescence　intensity　such　as　high　time　resolution　and　large　dynamic　range.　However,　some　negative　factors　limit　its　performance　in　practice.　In　this　work,　the　methods　for　weak　signal　detection　and　self-fitting　noise　suppression　were　applied　to　the　signal　processing　in　the　single-photon　counting　system　in　which　a　photomultiplier　tube　(PMT)　was　the　photoelectric　sensor.　Firstly,　the　weak　signal　from　PMT　was　amplified　by　two　stage　amplifiers　and　subtracted　by　its　means.　And　then　the　lost　pluses　were　corrected　by　double　discriminating　voltages　as　different　peaks＇　circumscriptions.　Lastly　it　was　proposed　to　put　program-controlled　auto　compensation　function　for　self-adjusting　ability　and　high　sensitivity.　By　these　methods,　the　measure　errors　caused　by　narrow　pulse　interval　and　double-photons　peak　are　decreased　whilst　the　counting　efficiency　is　increased.　It　was　demonstrated　that　the　performance　of　the　single-photon　counting　system,　in　which　signals　were　processed　with　the　proposed　methods,　was　enhanced　and　the　system　was　more　flexible　in　terms　of　self-fitting　measuring.