This invention relates to the break point debug method in the LR(k) random grammar position, its steps is: Defines language LR(k) grammar or LR(k) grammar subclass grammar G; Inserts the break point in the corresponding grammar position; Inspects each break point, if this break point establishes in some grammar position right middle of the production pattern, then adds the useless non-end mark, thus obtains new grammar G'; to generate the grammar G' analytical statement; to calculate the type of each break point; to analysis the input string, until meets a reduction operation, inspects this position whether corresponds a break point, if it is, then adopts the following: To the effective break point, suspends the parsing process, demonstrates the current analysis status messages; To the invalid break point, neglects this break point, continues the parsing process; To indefinite break point, then neglects or joints with current input string and the position the break point established, further judges this position whether effective or not, if this position of the current input string is effective, presses effective break point position processing, if this position is invalid, then neglects this position, continues the parsing process. This invention obviously increases the break point number which may track and debug, may track the fine grain grammar ingredient, helps the user to carry on the grammar debugging well, and reduces the development difficulty of analyzer.