The last breaker protection is usually installed in inverter station against the severe over-voltage caused by load shedding of AC system. A new last breaker protection design concept different from convention is adopted by ABB in ± 800kV Xiangjiaba-Shanghai UHVDC project. The comparative analysis of the last breaker protection in UHVDC and conventional HVDC projects is pursued with protection signal acquisition, protection logic, safety hazard etc. The limits of the last breaker protection designed in HVDC project and problems possibly occur in UHVDC project are pointed out. Finally, the corresponding suggestion is also presented. The study is helpful to improve the reliability of existing HVDC projects, and is useful for the operation and maintenance of future UHVDC projects.