The accurate spatial-temporal distribution of soil moisture,which is one of the important parameters of the Earth System Simulation,is the basis for land-atmosphere interaction.Both reanalysis data and the land data assimilation system (LDAS) can provide global or regional high-resolution soil moisture products.However,validation of the simulation data is required before application.In this study,the fidelity of soil moisture products,including four reanalyzed soil moisture products (ERA5,ERA5-Land,NCEP-DOE R2 and CRA40) and three LDAS soil moisture products (GLDAS-Noah,GLDAS-CLSM and CLDAS) are examined using the in situ datasets via several statistical indexes (e.g.,median,deviation,and correlation coefficient) in northern China.The results show that CRA40 achieves the best correlation with observations,while ERA5 and ERA5-Land respectively provide better simulation for dry and wet centers.In addition,GLDAS-Noah shows a slightly positive bias for drier soil areas,and CLDAS presents a negative bias for wet soil areas.In general,NCEP-DOE R2 and GLDAS-CLSM exhibit poor simulation in northern China.ERA5-Land,ERA5-Land,NCEP-DOE R2,GLDAS-Noah and CLDAS show simulated positive bias in all seasons.The better simulation results in spring are CRA40 and ERA5-Land,along with ERA5-Land,ERA5 and CRA40 in summer and autumn.In winter,the correlation between the soil moisture simulated by different products and the observed value is the smallest throughout the year.In arid regions,different soil moisture products exhibited positive deviations,with the GLDAS-Noah simulation being the best,but the peak and valley values of soil moisture in the simulated products appeared earlier than observed.GLDAS-Noah,CRA40 and ERA5 can more effectively simulate the duration of dry and wet soils and the amplitude of soil moisture changes in the monsoon region.Most of the products can simulate the occurrence of drier soils and wetter soils in the transition zone that is affected by the summer monsoon.