In this study, we used Generalized additive models (GAM) to explore the relationship between the catch per unit effort (CPUE) of swordtip squid (Uroteuthis edulis) fishery in northern Taiwan and environmental factors, included temporal factors (year, month, lunar day), the spatial factors (longitude, latitude, seabed depth), fishing performance factors (ship tonnage, the total horsepower, light intensity) and ocean environmental factors (sea surface temperature, chlorophyll a). The results show that the temporal factors, the spatial factors, and fishing performance factors affected CPUE of swordtip squid. However, the ocean environmental factors were no significant with CPUE of swordtip squid. In addition to changes in CPUE between years, each year in September, sixth in lunar calendar, in latitude 26-27°N, longitude 124-125°E, the depth of 125 meters, the ship tonnage of 125 tons, the total horsepower 1500 horsepower, and 500,000 kilowatts under the fishing boats, there may be a high CPUE.