The invention discloses a portable biological precision detecting instrument and detecting method. The detecting instrument is provided with a detecting box and a control box so as to achieve the control experiment effect during microbiological detection, meanwhile, cameras and automatic cell counting devices are arranged inside the detecting box and the control box and used for monitoring the microbial culture conditions, a control unit is used for processing monitoring results into visualized information, then the visualized information is displayed by a first display screen, and a second display screen, the first display screen and the second display screen are provided with telescopic drive devices to extend out of the instrument or retract into the instrument controllably so that the design space can be saved, and therefore the whole instrument is smaller and more exquisite and convenient to carry. The detecting instrument is further provided with a lifting electric heating device in a matched mode, so that proper culture temperatures are provided for organisms inside the detecting box and the control box. The portable biological precision detecting instrument is novel in design, high in portability and high in popularization value.