Contaminating food-borne pathogen such as Escherichia coli become one problem in food safety especially for agricultural product. Detection of the presence of pathogen may help customers to protect themselves against food-borne disease. Several simple techniques have been developing including the use of Total Plate Count (TPC). However, this method is time consumed resulting developing new approach in detecting E. coli including the use of specific bacteriophage. This research was aimed to isolate, formulate, and test the potency of bacteriophage in detecting E. coli which is isolated from post-harvest horticultural crops. About ten isolates were isolated from 5 traditional vegetable markets in Jember area. In addition, 2 kinds of bacteriophages were also isolated from vegetables and sewage for ϕPst-1 and ϕKR-1, respectively. Formulation of detection solution were based on Luria Bertani Modified Medium (LBMM) composted by LB + 1% Glucose (Glu) and 0.1% of Bromothymol Blue (BTB) which was selected based on stability of green-color at 570nm. Detection assay was also done using mixture of detection solution, sample, and bacteriophage ϕPsT-1 which was incubated at both room temperature and 37°C. The result showed that, the kit was able to determine the presence of E. coli about 4-5 hours depend on the incubation temperature. Negative result was shown by no color change while positive (contaminated by E. coli) result shown by the changing of color from green to yellow. Through this result we claimed that the technique is more efficient than TPC methods. 