The purpose of this research was to determine the structure, composition and level of weed species diversity in immature oil palm plantations (TBM) and producing palm oil (TM) in Manggaraya village, Tanjung Lago sub-district, Banyuasin district. The research was conducted from February to April 2018. Observation method, with sample sampling technique using purposive sampling with the quadratic method. Observation parameters were Density, frequency, Important Value Index (INP), and species diversity index. Research results were obtained. The composition of weeds in immature oil palm plantations (TBM) was found in 5 families, 12 species and 709 individuals. The oil palm weeds produced (TM) found 4 families, 9 species, and 537 individuals. The dominant weed structures in immature oil palm plantations (TBM) were Panicum repen, and Eleusine indica with INP values: 23.43, and the oil palm plantations produced were Mikania micrantha, with INP value: 31.57, and weed diversity index. on immature oil palm (TBM) 2.14, and the weed species diversity index for producing crops was 2.07. The level of diversity of gullma types of TBM and TM is categorized as moderate.Tujuan dari penelitian ini adalah untuk mengetahui struktur, komposisi dan tingkat keanekaragaman jenis gulma pada perkebunan sawit belum menghasilkan (TBM) dan kelapa sawit menghasilkan (TM) di desa Manggaraya, kecamatan Tanjung Lago, Kabupaten Banyuasin. Penelitian dilakukan dari Februari-April 2018. Metode observasi, dengan teknik pencuplikan sampel secara purposive sampling dengan metode kuadrat. Parameter pengamatan yaitu Kerapatan, Frequensi, Indeks Nilai penting (INP), dan indeks keanekaragaman jenis. Hasil penenilitian didapat Komposisi gulma pada perkebunan kelapa sawit belum menghasilkan (TBM) ditemui 5 Famili, 12 spesies dan 709 individu., dan Gulma kelapa sawit yang menghasilkan (TM) ditemui 4 famili, 9 spesies, dan 537 individu. Struktur gulma yang dominan pada perkebunan kelapa sawit belum menghasilkan (TBM) adalah Panicum repen, dan Eleusine indica dengan nilai INP: 23,43, dan Tanaman kelapa sawit menghasilkan adalah Mikania micrantha, dengan Nilai INP: 31,57, dan Indeks keanekaragamannya jenis gulma pada kelapa sawit belum menghasilkan (TBM) 2,14, dan indeks keanekaragaman jenis gulma pada tanaman menghasilka adalah 2,07. Tingkat keanekaragaman jenis gullma TBM dan TM dikategorikan sedang.