Alkaline phosphatase (AP) in the ocean strongly controls the marine phosphorus cycles, an essential element for marine life, which is often limited in the vast surface oceans. There are a number of hypotheses concerning a single environmental factor on AP activity (APA), however, a systematic study including all hypothesized factors on a global scale is still lacking. We investigate in this study the impact of environmental factors on APA using data from publications and databases. We find that DOP concentration, salinity, excess phosphate (P*) concentration and chlorophyll a concentration are critical environmental factors in predicting global patterns of APA, which together explains as much as 39% of spatial variance in the observed APA data. DOP concentration explains the most spatial variance in the observed APA data among all environmental factors and has a negative effect on APA. P* concentration has a negative effect on APA, while salinity and chlorophyll a concentration have a positive effect. Moreover, wind speed, dust iron deposition rate and zinc concentration are also important factors. Our results elucidate that on a global scale when phosphorus limitation is severe, plankton utilize DOP through production of AP to alleviate phosphorus limitation, resulting in the reduction of DOP concentration, and this process requires sufficient salinity levels and zinc and iron concentrations. More field APA measurements, particularly in the Indian and Pacific Oceans, are needed to reduce uncertainties in our conclusion.