Boundary layer convergence lines caused convective storms in Bohai Bay during 2008-2009 were analyzed. The results showed that: (1) In the hightemperature and high humidity environments under instable conditions of atmospheric stratification, a single landsea breeze convergence line is able to produce a weak convective storm in its endpoint. (2) The three cases that landsea breeze convergence line intersects the weak cold front, or two landsea breeze convergence lines intersect, or outflow boundary of thunderstorm meets with the boundary layer convergence line in coastal could produce strong convective storm. (3) Boundary layer convergence line triggering the convective storm in the Bohai Bay often occurs in July-August every year. Meanwhile, in the subtropical high eastward withdrawal process in the Bohai Bay, this atmospheric stratification maintains a high temperature, high humidity and instable condition. And then convergence line triggers convective storm, which moves along the convergence line, and its direction of movement depends on the dominant wind direction on both sides of convergence line. (4) Boundary layer convergence line triggering convective storm has its features of sudden, strong, and short duration. By analyzing the movement and evolution of landsea breeze convergence line, we may improve the nowcasting and warning of strong convective storm and reduce disasters.