泥河湾盆地发育着我国北方第四纪典型的河湖相沉积体系，因其间富集众多早-中更新世旧石器时代遗址为学术界所关注。本文对泥河湾盆地蔚县吉家庄遗址（JJZ-B和JJZ-E地点）的遗址成因进行分析。地貌和沉积物特点表明，JJZ-B地点埋藏于湖滨相环境的湿地或沼泽环境，JJZ-E地点则属于湖滨相环境下的沙坝沉积体系。遗物的多项指标（遗物空间分布特点、石制品风化磨蚀状况、石制品技术组合与空间产状特征等）分析显示，JJZ-B地点属于近原地埋藏，形成过程中受到微弱的入湖片流改造，遗址完整性较高；JJZ-E地点的遗物连同砾石被湖滨片流搬运至遗址堆积区，后期受到了湖水的淘洗作用，显示异地埋藏的特点。研究表明，泥河湾古湖在中更新世仍保留有丰富的古人类活动信息，湖滨不同部位对遗址成因产生重要影响；该研究对正确解读古人类对吉家庄遗址不同地点的利用方式具有重要意义。

Owing to low-energy hydraulic agents and fine-grained sediments, the fluvio-lacustrine basin proves to be ideal depositional system for preserving archaeological remains. The typical fluvio-lacustrine sediments in Nihewan Basin of North China are rich sources of Early to Middle Pleistocene archaeological sites, which offer an important opportunity to investigate human evolution and adaptive behaviors in East Asia. Comparing to the advances on the study of site formation processes of Lower Pleistocene sites have been handled in the basin, site formation focus on the Middle Pleistocene sites are yet to be carried out. In this paper, we present a site formation study of a newly discovered Middle Pleistocene archaeological site named Jijiazhuang site (JJZ) in Yuxian Basin (south part of Nihewan Basin). Two typical localities (JJZ-B and JJZ-E) are selected and geoarchaeological as well as archaeological factors are adopted for the site formation research. Through the analysis of geomorphology and deposits features, archaeological remains in JJZ-B were buried in marsh or swamp environment of lake margin deposits when the Nihewan old lake began retreating, while the archaeological sequence of JJZ-E probably belongs to the sand bar sedimentary face of lake margin environment. Multiple proxies from archaeological materials (artifacts spatial distribution, technological composition, weathering and abrasion condition, orientation as well as inclination) demonstrate that JJZ-B belongs to near primary context, the archaeological remains had been disturbed by low-energy sheet wash across the lake shore setting which provides effective information for exploring hominins technology and adaptive behaviors. Meanwhile, JJZ-E was preserved in secondary context where archaeological remains together with cobbles and pebbles were transported to accumulative area by relative high energetic hydraulic flow of lake wave and sheet wash, so that the locality witnessed low integrity of archaeological materials compared to JJZ-B. This study shows that the Nihewan Basin contains extensive information of archaeological remains of Middle Pleistocene. Formation processes of the different sites are strongly affected by the different settings in the archaeological landscape. Study on the site formation processes of JJZ site indicates that archaeological remains were in relative low density, and the formation processes varied from near primary context to secondary context. In addition, this study bears great significance on the study of the adaptive patterns of different localities of Jijiazhuang site complex by hominins during Middle Pleistocene.