Knowledge base provides a potential way to improve the intelligence of information retrieval (IR) systems, for that knowledge base has numerous relations between entities which can help the IR systems to conduct inference from one entity to another entity.Relation extraction is one of the fundamental techniques to construct a knowledge base.Distant supervision is a semi-supervised learning method for relation extraction which learns with labeled and unlabeled data. However, this approach suffers the problem of relation overlapping in which one entity tuple may have multiple relation facts. We believe that relation types can have latent connections, which we call class ties, and can be exploited to enhance relation extraction. However, this property between relation classes has not been fully explored before. In this paper, to exploit class ties between relations to improve relation extraction, we propose a general ranking based multi-label learning framework combined with convolutional neural networks, in which ranking based loss functions with regularization technique are introduced to learn the latent connections between relations. Furthermore, to deal with the problem of class imbalance in distant supervision relation extraction, we further adopt cost-sensitive learning to rescale the costs from the positive and negative labels. Extensive experiments on a widely used dataset show the effectiveness of our model to exploit class ties and to relieve class imbalance problem. Relation extraction (RE) aims to classify the relations (or called relation facts) between two given named entities from natural-language text. Fig. 1 shows two sentences with the same entity tuple but two different relation facts. RE is to accurately extract the corresponding relation facts (place of birth, place lived) for the entity tuple (Patsy Ramsey, Atlanta) based on the contexts of sentences. Supervised-learning methods require numerous labeled data to work well. With the rapid growth of volume of relation types, traditional methods can not keep up with the step for the limitation of labeled data. In order to narrow down the gap of data sparsity, [1] proposes distant supervision (DS) for relation extraction, which automatically generates training data by aligning a knowledge facts database (ie. Freebase [2]) to texts. For a fact (e.g. entity tuple with a relation type) from the knowledge base, the sentences containing the entity tuple in the fact are regarded as the training data.Class ties mean the connections (relatedness) between relations types for relation extraction. In general, we conclude that class ties can have two categories: weak class ties and strong class ties. Weak class ties mainly involve the co-occurrence of relations such as place of birth and place lived, CEO of and founder of. Besides, strong class ties mean that relations have latent logical entailments. Take the two relations of capital of and city of for example, if one entity tuple has the relation of capital of, it must express the relation fact of city of, be...