A method of determining whether copy number variation exists in a genome sample, comprising: sequencing the genome sample, to obtain a sequencing result consisting of a plurality of reads, wherein the genome sample is obtained from a single cell; aligning the sequencing result to a reference genome sequence, to determine a distribution of the reads in the reference genome sequence; determining a plurality of breakpoints in the reference genome sequence based on the distribution of the reads in the reference genome sequence, wherein the number of reads has significance at both sides of the breakpoints; determining a detection window in the reference genome based on the plurality of the breakpoints; determining a first parameter based on reads falling in the detection window; and determining whether the copy number variation exists in the genome sample against the detection window based on a difference between the first parameter and a preset threshold; wherein the step of determining a plurality of breakpoints in the reference genome sequence comprises the steps of dividing the reference genome sequence into a plurality of primary windows having a predetermined length, and determining reads falling in each of the plurality of the primary windows; for at least one site in the reference genome sequence, determining the number of reads falling in the same number of the plurality of primary windows at both sides of the site; and determining a p value of the site, wherein the p value represents that the number of reads falling in either side of the site has significance; wherein the site is the breakpoint, if the p value of the site is smaller than a final p value; wherein the step of determining the p value of the site further comprises: for the site, selecting the plurality of primary windows having the same number at either side of the site respectively, and calculating the relative number of reads falling in each of the plurality of primary windows R i, wherein i represents the number of the plurality of primary windows, subjecting all of the relative numbers of reads falling in the plurality of primary windows R i to a Run-Test, to thereby determine the p value of the site, wherein the relative number of reads is determined by following formula: R i = log 2 r i r ̅ wherein r i represents the number of reads falling in the i-th primary window, r ̅ = 1 n ∑ i = 1 n r i, n represents the total number of the plurality of primary windows. sequencing the genome sample, to obtain a sequencing result consisting of a plurality of reads, wherein the genome sample is obtained from a single cell; aligning the sequencing result to a reference genome sequence, to determine a distribution of the reads in the reference genome sequence; determining a plurality of breakpoints in the reference genome sequence based on the distribution of the reads in the reference genome sequence, wherein the number of reads has significance at both sides of the breakpoints; determining a detection window in the reference genome based on the plurality of the breakpoints; determining a first parameter based on reads falling in the detection window; and determining whether the copy number variation exists in the genome sample against the detection window based on a difference between the first parameter and a preset threshold; wherein the step of determining a plurality of breakpoints in the reference genome sequence comprises the steps of dividing the reference genome sequence into a plurality of primary windows having a predetermined length, and determining reads falling in each of the plurality of the primary windows; for at least one site in the reference genome sequence, determining the number of reads falling in the same number of the plurality of primary windows at both sides of the site; and determining a p value of the site, wherein the p value represents that the number of reads falling in either side of the site has significance; wherein the site is the breakpoint, if the p value of the site is smaller than a final p value; wherein the step of determining the p value of the site further comprises: for the site, selecting the plurality of primary windows having the same number at either side of the site respectively, and calculating the relative number of reads falling in each of the plurality of primary windows R i, wherein i represents the number of the plurality of primary windows, subjecting all of the relative numbers of reads falling in the plurality of primary windows R i to a Run-Test, to thereby determine the p value of the site, wherein the relative number of reads is determined by following formula: R i = log 2 r i r ̅ wherein r i represents the number of reads falling in the i-th primary window, r ̅ = 1 n ∑ i = 1 n r i, n represents the total number of the plurality of primary windows. for the site, selecting the plurality of primary windows having the same number at either side of the site respectively, and calculating the relative number of reads falling in each of the plurality of primary windows R i, wherein i represents the number of the plurality of primary windows, subjecting all of the relative numbers of reads falling in the plurality of primary windows R i to a Run-Test, to thereby determine the p value of the site, wherein the relative number of reads is determined by following formula: R i = log 2 r i r ̅ wherein r i represents the number of reads falling in the i-th primary window, r ̅ = 1 n ∑ i = 1 n r i, n represents the total number of the plurality of primary windows.