Pantai Maron, Pantai Tirang dan Pantai Mangunharjo Semarang memiliki hutan mangrove yang tumbuh secara alami dan buatan untuk mencegah erosi. Tujuan penelitian ini adalah mengetahui tekstur sedimen dan bahan organik, kelimpahan kepiting serta hubungan kelimpahan kepiting dengan bahan organik dan tekstur sedimen di kawasan hutan mangrove. Teknik pengambilan sampel menggunakan metode purposive sampling, dilakukan 3 kali pengulangan selama 3 minggu pada bulan Desember 2016. Langkah pertama dilakukan pengukuran parameter lingkungan; kedua diambil sampel kepiting dan sedimen, ketiga dilakukan analisis laboratorium, analisis tekstur sedimen dan analisis bahan organik, keempat perhitungan kelimpahan kepiting dan analisis korelasi Pearson. Hasil penelitian menunjukkan bahwa tekstur sedimen yang didapatkan pada ketiga stasiun yaitu clay (liat). Persentasi liat 59,80% - 74,99% dengan persentasi tertinggi pada Pantai Maron. Fraksi sand (pasir) 22,44% - 38,29% dengan persentasi tertinggi pada Pantai Tirang. Fraksi silt (lumpur) 1,83% - 2,57% dengan persentasi tertinggi pada Pantai Maron. Kandungan bahan organik 7,33% - 9,33% dengan persentasi tertinggi pada Pantai Maron. Kepiting yang didapatkan pada ketiga stasiun yaitu Metopograpsus latifrons dan Scylla serrata. Struktur komunitas kepiting didapatkan nilai kelimpahan stasiun I 5720 ind/m2, stasiun II 5432 ind/m2 dan stasiun III 5802 ind/m2. Indeks keanekaragaman kepiting dalam kategori rendah dan hubungan tekstur sedimen dengan bahan organik memiliki hasil yang sedang. Hubungan tekstur sedimen dengan kelimpahan kepiting memiliki hasil korelasi yang sedang dan hasil dari hubungan bahan organik dengan kelimpahan kepiting memiliki hasil korelasi yang sedang. Maron Beach, Tirang Beach and Mangunharjo Beach Semarang have mangrove forests that grow both naturally and artificially to prevent erosion. The purpose of this research are to analyze the texture of sediment and organic material, crab abundance, and the relation of crab abundance with organic material and sediment texture in mangrove forest area. The sampling technique used in this research is purposive sampling method, with 3 repetitions conducted in three weeks in December 2016. The first step was the measurement of environmental parameters. The second step was samples collections of crabs and sediments. The third step conducted was laboratory analysis on sediment texture and organic material. The last step was to calculate crab abundance and perform Pearson correlation analysis. The results showed that the sediment texture obtained in three stations was clay. Clay percentage was 59.80% - 74.99% with the highest percentage on Maron Beach. Sand fraction percentage was 22.44% - 38.29% with the highest percentage on Tirang Beach. The silt fraction was 1.83% - 2.57% with the highest percentage on Maron Beach. The content of organic materials is 7.33% - 9.33% with the highest percentage on Maron Beach. Crabs in the three stations obtained are Metopograpsus latifrons and Scylla serrata. Crab abundance on station I is 5720 ind / m2, while on station II and station III is 5432 ind / m2 and 5802 ind / m2, respectively. The index of crab diversity is low and the relationship of sediment texture with organic matter is moderate. The relationship of sediment texture with crab abundance has a moderate correlation, while the relationship of organic material with crab abundance also has a moderate correlation result.