The key equipment lightweight of the flexible DC converter platform is a crucial problem for achieving economically efficient offshore wind power transmission. Starting from the existing design scheme of bridge arm reactors in the flexible DC converter valve, two lightweight bridge arm reactor schemes, namely the multiplexing and the distributed bridge arm reactor of flexible DC transformer are proposed. The design methods for bridge arm reactor parameters of two lightweight schemes is also elucidated. Based on PSCAD/EMTDDC simulation software, the models of the offshore wind power pseudo-bidirectional flexible DC transmission system based on two lightweight bridge arm reactor schemes are established, separately. And the steady-state and transient characteristics of lightweight bridge arm reactor schemes and the traditional bridge arm reactor schemes are compared and analyzed. The results indicate that after the DC double-pole short-circuit fault occurs, the maximum bridge arm current using two lightweight bridge arm reactor schemes does not exceed 1.2 p.u., and there is no significant drop in sub-module capacitor voltage. Further more, when the converter is locked, it shows that the transformer valve-side voltage of the lightweight bridge arm reactor scheme decreases significantly compared to that of traditional bridge arm reactor schemes.