The objective was to probe the site where the biosynthesis of chlorophyll was blocked under Mo deficiency at low temperature, which led to the decrease of chlorophyll in winter wheat cultivars. The intermediates of chlorophyll biosyn- thesis were analyzed in winter wheat cultivars in soil culture, miniblock culture, and solution culture to study the effects of Mo on chlorophyll biosynthesis without Mo addition (CK, soil available Mo 0.112 mg kg-1) and Mo addition (+ Mo, 0.13 mg kg-1 Mo was added). Laevulinic acid (LA), the competitive analog of δ-aminolaevulinic acid (ALA) was also introduced in the experiment. The ratio of Chl a/Chl b was constant between CK and + Mo treatment, whereas it increased at low temperature, which indicated that Mo deficiency did not inhibit the transformation of Chl a to Chl b at low temperature. Under Mo deficiency, the contents of protochlorophyll (Pchl), Mg-protoporphyrin Ⅸ (Mg-Proto Ⅸ), protoporphyrin Ⅸ (proto Ⅸ), and uroporphyrinogen Ⅲ (Uro Ⅲ) decreased [Uro Ⅲ decreased significantly (P < 0.01)], whereas ALA and glutamate increased significantly (P < 0.01) compared with that of Mo addition, which suggested that the transformation from ALA to Uro Ⅲ might be inhibited. The content of ALA reversed after addition of LA, it was significantly higher (P < 0.01) in Mo addition than in CK. The results indicated that the transformation from ALA to Uro Ⅲ was blocked under Mo deficiency, which resulted in the inhibition of the biosynthesis of chlorophyll and led to the decrease of chlorophyll in winter wheat cultivars. The objective was to probe the site where the biosynthesis of chlorophyll was blocked under Mo deficiency at low temperature, which led to the decrease of chlorophyll in winter wheat cultivars. The intermediates of chlorophyll biosyn- thesis were analyzed in winter wheat cultivars in soil culture, miniblock culture, and solution culture to study the effects of Mo on chlorophyll biosynthesis without Mo addition (CK, soil available Mo 0.112 mg kg -1) and Mo addition (+ Mo, 0.13 mg kg -1 Mo was added). Laevulinic acid ( The ratio of Chl a / Chl b was constant between CK and + Mo treatment, but it increased at low temperature, which indicates that Mo deficiency (LA), the competitive analog of δ-aminolaevulinic acid (ALA) was also introduced in the experiment Under inhibitory transformation of Chl a to Chl b at low temperature. Under Mo deficiency, the contents of protochlorophyll (Pchl), Mg-protoporphyrin IX (Mg-Proto IX), protoporphyrin IX (proto IX), and uroporphyrinogen IIICompared with that of Mo addition, which suggested that the transformation from ALA to Uro III might be inhibited. The content of ALA to Uro Ⅲ was blocked under Mo deficiency, which resulted in the inhibition of the biosynthesis of chlorophyll (P <0.01) in Mo addition than CK and led to the decrease of chlorophyll in winter wheat cultivars.