According to the Nielsens theorem and the basic idea of entanglement concentration, we improve and extend the deterministic entanglement concentration protocol that extracts one pair of maximally entangled particles out of two pairs of non-maximally entangled particles, thus establishing a deterministic entanglement concentration protocol that extracts two pairs of maximally entangled particles out of three pairs of non-maximally entangled particles in the way of the classical communication and local operation and the specific positive operator-valued measure. This is helpful for establishing a deterministic entanglement concentration protocol that extracts k pairs of maximally entangled particles out of n pairs of non-maximally entangled particles.