A vortex with heavy rainfall typical of disturbance over the Meiyu front occurred in the period of July 31 to August 1, 1980 The development and structure characteristics of this meso-β scale low are studied. The low bears clear baroclinity with the front structure different from heat lows in the area. The wind velocity and thermodynamic fields of the low are asymmetric with the strongest ascending motion at its warm sector. Based on the formula K=K_Ψ+K_χ-J(Ψ, Χ), we have calculated the kinetic energy of the divergent and rotational parts of the winds and their conversion. Investigation of the kinetic energy feature of the low suggests that the transfer from K_χ to K_Ψ occurs in its whole life cycle, especially in lower levels. The terms of f▽Ψ·▽χ and ▽²Ψ·▽Ψ·▽χ play a mojor role in the conversion similar to the situation in explosive cyclogenesis.