The distribution of chlorophyll a (ChL.a) concentration, primary production and new production were observed in Laizhou Bay of Bohai Sea in spring and neap tides during July 1997. The results showed that there were marked features of spatial zonation in the surveyed area, due to the differences between the geographic environment and the hydrological conditions. Chl. a, primary production and new production were all higher in spring tide than in neap tide in Laizhou Bay. The highest values of these parameters were encountered in the central coastal regions of the Bay. In most stations. Chl. a concentrations at the bottom were higher than that at the surface. The results of size-fractionated Chl. a and primary production showed that contributions of nano-plus pico-plankton (<20 μm) to total Chl. a and primary production were in dominant position in the phyto-plankton community biomass and production of Laizhou Bay. The major sources of nitrate of Laizhou Bay were terrestrial input and resuspension of the sediments in the estuary area. The environmental factors, governing primary production and new production in this sea area are discussed and comparisons of primary production and new production between spring tide and neap tide Laizhou Bay and other sea areas are also given.