Existing long-read assemblers require thousands of central processing unit hours to assemble a human genome and are being outpaced by sequencing technologies in terms of both throughput and cost. We developed a long-read assembler wtdbg2 (https://github.com/ruanjue/wtdbg2) that is 2-17 times as fast as published tools while achieving comparable contiguity and accuracy. It paves the way for population-scale long-read assembly in future.