Hydrothermal liquefaction (HTL) has recently received increasing attention due to its advantages in rapid reaction, using wet feedstock with no lipid-content restriction. These characteristics make HTL especially suitable for conversion of wet biomass into biocrude oil. In this talk, we will discuss the state-of-the-art advances and critical issues of HTL, including (1) Elemental distribution and migration; (2) Biocrude production and product valorisation; (2) Reactor design and engineering challenges. Specially, we will report our recent work on HTL and discuss the important role of HTL for the valorisation and biorefinery of low-grade algae, agricultural wastes and other biowastes. In addition to biocrude production, we will present our efforts to recovery energy and resources from post HTL streams, via biochemical (biohydrogen, biomethane and biohythane) or microbial electrochemical approaches.