Manned lunar exploration, again, becomes a research focus in recent years, and a number of the leading countries and regions, have announced their own programs. Beyond moon landing, scientists and engineers have started paying more attention on construction techniques for lunar habitation base. This paper introduces a new conceptual structural design of an erectable lunar habitat, using prefabricated building blocks made from the in-situ lunar regolith. The flank wall and foundation of the lunar habitat are fabricated by cubic blocks, among which joggle joint is adopted. Moreover, the roof is erected by arch segments with joggle joint as well and a 2m-thick lunar regolith layer is placed on top to shield the whole structure against the hostile environment. As to the environmental conditions on the Moon (1/6 of the earth gravity, temperature variation of approximate 300K within a lunar day and frequent moonquake), those loads, which would be regarded as irregular on earth, are actually regular for our lunar habitat structure. In order to investigate the behavior of the structure under such extreme loading, a 2D numerical model is established using the finite element software, ABAQUS. In this preliminary study, responses of the habitat structure under static loads of self-weight, overburden pressure, internal air pressure and temperature variation, are simulated. The simulation results give us some requirements on the structural design of this erectable lunar habitat. Several concluding remarks are drawn for both the building block system and the In-Situ Resource Utilization (ISRU) technique of lunar regolith.