A new type of simplified assembly without “water rod” or solid moderator is identified to simplify China Supercritical Water-cooled Reactor with the rated electric power of 1000 MWel (CSR1000) core structure. A study on the properties of this new assembly has been carried out. Under the condition of heat full power, maximum cladding surface temperature (MCST) is 658 °C, very close to safety criterion 650 °C, and maximum linear heat generation rate (MLHGR) is 40.0 kW/m, slightly higher than safety criterion 39 kW/m. Considering rod stuck criterion, the maximum keff is 0.9833, lower than safety criterion 0.99. The discharge burn-up reduced to 21368 MWd/t, a sharp decreasing of 31.1%. This simplified assembly provides a new idea for solving the problem of complex structure of supercritical water-cooled reactor (SCWR).