Rembang Regency located in the northeastern part of Central Java which has 106.66 ha mangrove rehabilitation area. Mangrove ecosystem in Rembang has been managed by local communities and NGOs for eco-tourism. The local people also have actively cleared mangrove area for artificial ponds that are put an ecological pressure into mangrove ecosystem function. One of the important impact that needs to be concerned is the disruption of vital habitat as well as the development of fish larvae in mangrove area. The purpose of this study was to determine the type of fish larvae families, distribution, abundance, uniformity, diversity and dominance of larval fish in in the mangrove ecosystem of Pasar Banggi, Rembang. The samplings were conducted in April 2016 three times, with intervals one week. The sampling method was done by stratified sampling method. In three times sampling we obtained seven families of fish larvae in the following name: Gerreidae, Gobiidae, Clupeidae, Engraulidae, Adrianichtyidae, Megalopidae and Carangidae. The diversity indices range between 0,087- 0,770, with the highest in level in mangrove area with mangrove age of three years. The uniformity index ranges between 0,062 – 0,555, the highest value is also in mangrove area with mangrove age of three years. The dominance index values ranging between 0,577 – 0,972, with the highest value in the in mangrove area with mangrove age of fifty years. Highest abundance of fish larvae were caught among the sites acquired in the area A ( mangrove area about fifty years ) is 40 Ind / m3 , region B ( mangrove area about seven years ) of 22 Ind / m3 and the lowest is the area C ( mangrove area about three years old ) by 19 Ind / m3