Pekalongan City is a coastal city where there is a type B port, the largest Pekalongan Nusantara Fisheries Port (Pelabuhan Perikanan Nusantara Pekalongan) in Central Java Province. Pekalongan PPN has a fish auction facility that functions to market fishery products. one of the fish that is mostly obtained by fishermen is flying fish with a total production in 2017 of 7,423,959 kg. This study aims to determine the development of flying fish production in Pekalongan, the behavior of prices at the producer level at the fish auction site and the level of consumers in Pasar Banjarsari, as well as the efficiency of marketing flying fish by using market integration in Pekalongan City. This research uses descriptive analysis method with the Index of Market Connection (IMC) approach. The data used are secondary data obtained from the Department of Marine and Fisheries of Pekalongan City(Dinas Perikanan dan Kelautan Pekalongan), the data analyzed in the form of monthly production of flying fish, monthly price data of flying fish in the producer market, and consumer / retail markets in Pekalongan City. The results of the study indicate that the first flying fish production fluctuates every month. second, the behavior of flying fish in the producer market and the consumer market shows that it is unstable or fluctuating as seen from the value of KV which is above 9% both at the producer level and at the consumer level. The third result, the IMC value is smaller than one, which is 0.73 and the value of b2 is greater than 0.5, which is 0.861062, which means that the integration of the flying fish market in the producer market and consumer market in the short and long term is strong, so it can be said marketing of flying fish in Pekalongan City is efficient.