本文建立一包括頻道商、系統業者及收視戶之有線電視區域市場模型o此模型將有線電視區域市場區分為上游市場：由頻道商及區域系統業者形成之寡佔異質商品競爭市場；下游市場：由區域系統業者及該區收視戶形成之區域獨佔市場或區域寡佔價格競爭市場。在上游為寡佔異質商品競爭的市場條件下，比較有線電視區域市場之下游為獨佔及寡佔價格競爭兩種區域市場結構，本文導出：若節目品質與授權費相同，下游為獨佔時收視費較高；若頻道數目超過系統最大容量限制且收視費相同，下游為寡佔價格競爭時節目品質較高。此隱含：單就消費者剩餘而論，有線電視區域市場之下游為寡佔價格競爭之市場結構優於下游為獨佔之市場結構。繼續進行福利分析，我們獲致以下結論：1.頭端設備、主幹線及主幹線放大器等成本越低，下游寡佔價格競爭所產生之社會福利效果越大。2.過度的下游競爭導致社會福利之下降。

A theoretical model is proposed to analyze the local market structrue of CATV. Vertically, we divide the local market of CATV into the upstream market where channel program providers trade with local systems and the downstream markets where local systems trades with consumers. It is supposed that the upstream market is a differentiated oligopoly. Two cases of the downstream markets are considered: the local monopoly (1 system) and the local oligopoly with price competi­tion (2 or more systems). Compare these local market structures, we find that if the program quality and the authorized fee are equivalent, the subscription price is higher in case of local monopoly, and if the number of channels exceeds the system capacity and the subscription prices are equal, the program quality is higher in case of local oligopoly with price competition. This implies that the consumer surplus of local monopoly is lower. By welfare analysis, we also derive: 1.The less of the costs of headend equipment, of trunk line, and of signal amplifier, the more advantage of the local oligopoly, and 2, Exceeding competition in downstream market induces lower social welfare.