Doppler radar reflectivity and the surface automatic weather stations (AWS) wind observations demonstrate that the mesoscale cyclonic eddies at the low level are active in the spiral-cloud bands of landfalling typhoon Matsa. Numerical simulation has been carried out to investigate the evolution characteristics of typhoon Matsa in 2005 after its landfalling by using the new-generation mesoscale weather research and forecasting (WRF) model, and the four-dimensional variational Dopple radar analysis system (4D-VDRAS) is used to retrieve single-Doppler velocity. Then a preliminary study has been made on the mesoscale features of typhoon Matsa after landfalling in parallel with diagnostic analyses of the conversion of kinetic energy and vorticity between typhoon Matsa and mesoscale systems on the area mean basis. Results show that: (1) The results of numerical simulation and Doppler radial velocity retrieval indicate that the mesoscale cyclonic eddies at the low level are active in the spiral-cloud bands of landfalling typhoon Matsa, and there is severe mesoscale upward movement accompanying the mesoscale cyclonic eddies. The stronger the mesoscale upward movement is, the larger Doppler radar reflectivity is.(2) The diagnostic results of the kinetic energy conversion between Matsa and mesoscale systems demonstrate that the mesoscale cyclonic eddies at the low level obtain kinetic energy from landfalling typhoon Matsa to develop, whilst Matsa obtains kinetic energy from the mesoscale disturbances in the upper layers to be sustained after landfalling.(3) The diagnostic results of the vorticity conversion between Matsa and mesoscale systems show that Matsa obtains positive vorticity from the mesoscale cyclonic eddies at the low levels by means of the mesoscale upward movement, but in the upper layers, both the mesoscale horizontal and vertical movements play important roles. Therefore, the positive cyclonic vorticity is transported continuously to Matsa, and Matsa could be sustained for a long time after landfalling.