Abstract: Using observational data,radar products and the ERA5 reanalysis data,the mechanism of a cold front occurred in Baoding,Hebei province on April 15th,2021,was studied.It shows that:（1）There was a mass of dry and cold air at upper level overlapping a mass of warm air at low level,with a relative low humidity for the whole atmospheric layer.Surface wind speed increased during the passing of the cold front,and triggered dry convection which formed the outflow of the cold pool,thus further strengthened surface wind speed and turbulence accompanied by sand blowing.（2）There was weak radial wind zone inner convective cloud with the radial velocity close to zero,and the radar echo intensity on the rear of the weak radial wind zone increased.Meanwhile,hydrometer gathered and grew above the region with radial velocity at lower elevation angle equal to zero,while the radial velocity ranged from 5 to 10 m/s in the growth region of the hail,and the radial velocity at each elevation angle above hail area was zero as well.（3）The dry convective gale was trigger by downburst and downwardtransport momentum,and further strengthened by the evaporation and drag of rain droplets,with the former contribute more.（4）The northwesterly wind weakened and the cold front moved eastward after the decay of dry convection,leading to the ending of sand weather.A weak near-surface wind flux induced a relative slower falling velocity of dust particles,the near-surface visibility thus improved,while the PM₁₀ concentration was still relatively high.（5）The cold air descended at night,then the accompanied dust particles transported from the upwind regions deposited,leading to a floating dust weather.