The invention provides a rock brittleness index calculation and well logging interpretation method considering sedimentation and diagenetic processes, comprising the following steps: firstly, performing rock slice data organization; secondly, according to a rock component result of each slice, calculating a sedimentation component item; thirdly, according to buried depths of all the slices, calculating a compaction item; fourthly, according to a cement content of all the slices, calculating a cementation item; fifthly, calculating a rock brittleness factor; sixthly, according to the rock brittleness factor of all the slice samples, calculating a rock brittleness index; and seventhly, according to well logging data, establishing a rock brittleness index well logging interpretation method through rock electricity calibration. The rock brittleness index calculation and well logging interpretation method considering the sedimentation and diagenetic processes provides a rock brittleness evaluation method which is comprehensive, rapid and easy to calculate and obtain for rock brittleness evaluation on site and has a broad application prospect in rock brittleness evaluation on an oil field site.