15Background. BGISEQ-500 is based on DNBSEQ TM technology and superior in 16 providing high outputs and requiring less cost. This sequencer has been widely used in 17 various areas of scientific and clinical research. A better understanding of the sequencing 18 process and sequencer performance is essential for stabilizing sequencing process, 19 accurately interpreting sequencing results and efficiently solving sequencing troubles. To 20 solve these problems, a comprehensive database SEQdata-BEACON was constructed to 21 accumulate sequencing performance data in BGISEQ-500. 22 Methods. Totally 60 BGISEQ-500 sequencers in BGI-Wuhan lab were used to collect the 23 sequencing performance data. Those lanes in paired-end 100 sequencing using 10bp 24 2 barcode were chosen, and each lane containing 66 metrics was assigned a unique entry 25 number as ID. The database was constructed in MySQL server 8.0 and the website was 26 built on Apache (2.4.33 win64 VC15 server). The statistical analysis and linear regression 27 models were generated by R program based on the data from Results. A total of 2236 entries were recorded in the database, including sample ID, 30 yield, quality, machine state and supplies information. According to correlation matrix, 31 the 52 numerical metrics were clustered into three groups signifying yield-quality, 32 machine state and sequencing calibration. The metrics distributions also delivered some 33 patterns and rendered clues for further explanation or analysis of the sequencing process. 34 Using the data of total 200 cycles, the linear regression model well simulated the final 35 outputs. Moreover, the predicted final yield could be provided in the 15 th cycle of the 36 early stage of sequencing and the corresponding coefficient of determination R 2 of the 37 200 th and 15 th cycle models were 0.97 and 0.81 respectively. The data source, statistical 38 findings and application tools were all available in our website 39 http://seqBEACON.genomics.cn:443/home.html. These resources can be used as a 40 constantly updated reference for BGISEQ-500 users to comprehensively understand 41 DNBSEQ TM technology, solve sequencing problems and optimize the sequencing 42 process.43