A system for detecting biological particles adapted to detect and collect target biological particles, comprising: a dilution apparatus comprising a microfluidic channel, a sample tray assembly, and a first optical detection module, wherein the microfluidic channel has a first end and a second end; the first end of the microfluidic channel is connected to a sample reservoir, and the sample reservoir provides a sample comprising the target biological particles; the first optical detection module provides a first optical pathway; the first optical pathway passes through the microfluidic channel and is adapted to detect the target biological particles; the sample tray assembly comprises at least one sample tray for receiving a sample with the target biological particles that is detected; a selectively capturing apparatus comprising a second optical detection module and a capturing device; the sample tray is controlled to move to the selectively capturing apparatus and locate at a position where the second optical detection module corresponds to the sample tray; the second optical detection module locates the accurate position of each of the target biological particles on the sample tray; the capturing device is connected to the second optical detection module by a signal; after the second optical detection module locates the accurate position of each of the target biological particles on the sample tray, the capturing device is controlled to move to the accurate position of each of the target biological particle and to capture the target biological particle; then, the capturing device is controlled to load the target biological particle that is captured to a collection plate. a dilution apparatus comprising a microfluidic channel, a sample tray assembly, and a first optical detection module, wherein the microfluidic channel has a first end and a second end; the first end of the microfluidic channel is connected to a sample reservoir, and the sample reservoir provides a sample comprising the target biological particles; the first optical detection module provides a first optical pathway; the first optical pathway passes through the microfluidic channel and is adapted to detect the target biological particles; the sample tray assembly comprises at least one sample tray for receiving a sample with the target biological particles that is detected; a selectively capturing apparatus comprising a second optical detection module and a capturing device; the sample tray is controlled to move to the selectively capturing apparatus and locate at a position where the second optical detection module corresponds to the sample tray; the second optical detection module locates the accurate position of each of the target biological particles on the sample tray; the capturing device is connected to the second optical detection module by a signal; after the second optical detection module locates the accurate position of each of the target biological particles on the sample tray, the capturing device is controlled to move to the accurate position of each of the target biological particle and to capture the target biological particle; then, the capturing device is controlled to load the target biological particle that is captured to a collection plate.